--- a/dom/ipc/Makefile.in
+++ b/dom/ipc/Makefile.in
@@ -17,20 +17,17 @@ EXPORT_LIBRARY = 1
 ifndef _MSC_VER
 FAIL_ON_WARNINGS := 1
 endif # !_MSC_VER
 
 ifneq (cocoa,$(MOZ_WIDGET_TOOLKIT))
 TEST_DIRS += tests
 endif
 
-EXPORTS = \
-  nsICachedFileDescriptorListener.h \
-  PCOMContentPermissionRequestChild.h \
-  $(NULL)
+EXPORTS = PCOMContentPermissionRequestChild.h
 
 EXPORTS_NAMESPACES = \
   mozilla \
   mozilla/dom \
   mozilla/dom/ipc \
   $(NULL)
 
 EXPORTS_mozilla = \

--- a/dom/ipc/PBrowser.ipdl
+++ b/dom/ipc/PBrowser.ipdl
@@ -26,17 +26,16 @@ include "mozilla/layout/RenderFrameUtils
 
 using IPC::Principal;
 using gfxMatrix;
 using gfxRect;
 using gfxSize;
 using mozilla::layers::LayersBackend;
 using mozilla::layers::FrameMetrics;
 using mozilla::layout::ScrollingBehavior;
-using mozilla::void_t;
 using mozilla::WindowsHandle;
 using nscolor;
 using nsCompositionEvent;
 using nsIMEUpdatePreference;
 using nsIntPoint;
 using nsIntRect;
 using nsIntSize;
 using nsKeyEvent;
@@ -286,18 +285,16 @@ child:
      * |Show()| and |Move()| take IntSizes rather than Rects because
      * content processes always render to a virtual <0, 0> top-left
      * point.
      */
     Show(nsIntSize size);
 
     LoadURL(nsCString uri);
 
-    CacheFileDescriptor(nsString path, FileDescriptor fd);
-
     UpdateDimensions(nsRect rect, nsIntSize size, ScreenOrientation orientation) compress;
 
     UpdateFrame(FrameMetrics frame) compress;
 
     /**
      * Requests handling of a double tap. |point| is in CSS pixels, relative to
      * the scroll offset. This message is expected to round-trip back to
      * ZoomToRect() with a rect indicating where we should zoom to.

--- a/dom/ipc/TabChild.cpp
+++ b/dom/ipc/TabChild.cpp
@@ -13,17 +13,16 @@
 #include "ContentChild.h"
 #include "IndexedDBChild.h"
 #include "mozilla/ClearOnShutdown.h"
 #include "mozilla/IntentionalCrash.h"
 #include "mozilla/docshell/OfflineCacheUpdateChild.h"
 #include "mozilla/dom/PContentChild.h"
 #include "mozilla/dom/PContentDialogChild.h"
 #include "mozilla/ipc/DocumentRendererChild.h"
-#include "mozilla/ipc/FileDescriptorUtils.h"
 #include "mozilla/layers/AsyncPanZoomController.h"
 #include "mozilla/layers/CompositorChild.h"
 #include "mozilla/layers/PLayersChild.h"
 #include "mozilla/layout/RenderFrameChild.h"
 #include "mozilla/StaticPtr.h"
 #include "mozilla/unused.h"
 #include "mozIApplication.h"
 #include "nsComponentManagerUtils.h"
@@ -33,17 +32,16 @@
 #include "nsEventListenerManager.h"
 #include <algorithm>
 #ifdef MOZ_CRASHREPORTER
 #include "nsExceptionHandler.h"
 #endif
 #include "mozilla/dom/Element.h"
 #include "nsIAppsService.h"
 #include "nsIBaseWindow.h"
-#include "nsICachedFileDescriptorListener.h"
 #include "nsIComponentManager.h"
 #include "nsIDocumentInlines.h"
 #include "nsIDOMClassInfo.h"
 #include "nsIDOMElement.h"
 #include "nsIDOMEvent.h"
 #include "nsIDOMWindow.h"
 #include "nsIDOMWindowUtils.h"
 #include "nsIDocShell.h"
@@ -118,108 +116,16 @@ ContentListener::HandleEvent(nsIDOMEvent
 
 class ContentDialogChild : public PContentDialogChild
 {
 public:
   virtual bool Recv__delete__(const InfallibleTArray<int>& aIntParams,
                               const InfallibleTArray<nsString>& aStringParams);
 };
 
-class TabChild::CachedFileDescriptorInfo
-{
-    struct PathOnlyComparatorHelper
-    {
-        bool Equals(const nsAutoPtr<CachedFileDescriptorInfo>& a,
-                    const CachedFileDescriptorInfo& b) const
-        {
-            return a->mPath == b.mPath;
-        }
-    };
-
-    struct PathAndCallbackComparatorHelper
-    {
-        bool Equals(const nsAutoPtr<CachedFileDescriptorInfo>& a,
-                    const CachedFileDescriptorInfo& b) const
-        {
-            return a->mPath == b.mPath &&
-                   a->mCallback == b.mCallback;
-        }
-    };
-
-public:
-    nsString mPath;
-    FileDescriptor mFileDescriptor;
-    nsCOMPtr<nsICachedFileDescriptorListener> mCallback;
-    bool mCanceled;
-
-    CachedFileDescriptorInfo(const nsAString& aPath)
-      : mPath(aPath), mCanceled(false)
-    { }
-
-    CachedFileDescriptorInfo(const nsAString& aPath,
-                             const FileDescriptor& aFileDescriptor)
-      : mPath(aPath), mFileDescriptor(aFileDescriptor), mCanceled(false)
-    { }
-
-    CachedFileDescriptorInfo(const nsAString& aPath,
-                             nsICachedFileDescriptorListener* aCallback)
-      : mPath(aPath), mCallback(aCallback), mCanceled(false)
-    { }
-
-    PathOnlyComparatorHelper PathOnlyComparator() const
-    {
-        return PathOnlyComparatorHelper();
-    }
-
-    PathAndCallbackComparatorHelper PathAndCallbackComparator() const
-    {
-        return PathAndCallbackComparatorHelper();
-    }
-
-    void FireCallback() const
-    {
-        mCallback->OnCachedFileDescriptor(mPath, mFileDescriptor);
-    }
-};
-
-class TabChild::CachedFileDescriptorCallbackRunnable : public nsRunnable
-{
-    typedef TabChild::CachedFileDescriptorInfo CachedFileDescriptorInfo;
-
-    nsAutoPtr<CachedFileDescriptorInfo> mInfo;
-
-public:
-    CachedFileDescriptorCallbackRunnable(CachedFileDescriptorInfo* aInfo)
-      : mInfo(aInfo)
-    {
-        MOZ_ASSERT(NS_IsMainThread());
-        MOZ_ASSERT(aInfo);
-        MOZ_ASSERT(!aInfo->mPath.IsEmpty());
-        MOZ_ASSERT(aInfo->mCallback);
-    }
-
-    void Dispatch()
-    {
-        MOZ_ASSERT(NS_IsMainThread());
-
-        nsresult rv = NS_DispatchToCurrentThread(this);
-        NS_ENSURE_SUCCESS_VOID(rv);
-    }
-
-private:
-    NS_IMETHOD Run()
-    {
-        MOZ_ASSERT(NS_IsMainThread());
-        MOZ_ASSERT(mInfo);
-
-        mInfo->FireCallback();
-        return NS_OK;
-    }
-};
-
 StaticRefPtr<TabChild> sPreallocatedTab;
 
 /*static*/ void
 TabChild::PreloadSlowThings()
 {
     MOZ_ASSERT(!sPreallocatedTab);
 
     nsRefPtr<TabChild> tab(new TabChild(TabContext(), /* chromeFlags */ 0));
@@ -1208,140 +1114,16 @@ TabChild::RecvLoadURL(const nsCString& u
 
 #ifdef MOZ_CRASHREPORTER
     CrashReporter::AnnotateCrashReport(NS_LITERAL_CSTRING("URL"), uri);
 #endif
 
     return true;
 }
 
-bool
-TabChild::RecvCacheFileDescriptor(const nsString& aPath,
-                                  const FileDescriptor& aFileDescriptor)
-{
-    MOZ_ASSERT(NS_IsMainThread());
-    MOZ_ASSERT(!aPath.IsEmpty());
-
-    // aFileDescriptor may be invalid here, but the callback will choose how to
-    // handle it.
-
-    // First see if we already have a request for this path.
-    const CachedFileDescriptorInfo search(aPath);
-    uint32_t index =
-        mCachedFileDescriptorInfos.IndexOf(search, 0,
-                                           search.PathOnlyComparator());
-    if (index == mCachedFileDescriptorInfos.NoIndex) {
-        // We haven't had any requests for this path yet. Assume that we will
-        // in a little while and save the file descriptor here.
-        mCachedFileDescriptorInfos.AppendElement(
-            new CachedFileDescriptorInfo(aPath, aFileDescriptor));
-        return true;
-    }
-
-    nsAutoPtr<CachedFileDescriptorInfo>& info =
-        mCachedFileDescriptorInfos[index];
-
-    MOZ_ASSERT(info);
-    MOZ_ASSERT(info->mPath == aPath);
-    MOZ_ASSERT(!info->mFileDescriptor.IsValid());
-    MOZ_ASSERT(info->mCallback);
-
-    // If this callback has been canceled then we can simply close the file
-    // descriptor and forget about the callback.
-    if (info->mCanceled) {
-        // Only close if this is a valid file descriptor.
-        if (aFileDescriptor.IsValid()) {
-            nsRefPtr<CloseFileRunnable> runnable =
-                new CloseFileRunnable(aFileDescriptor);
-            runnable->Dispatch();
-        }
-    } else {
-        // Not canceled so fire the callback.
-        info->mFileDescriptor = aFileDescriptor;
-
-        // We don't need a runnable here because we should already be at the top
-        // of the event loop. Just fire immediately.
-        info->FireCallback();
-    }
-
-    mCachedFileDescriptorInfos.RemoveElementAt(index);
-    return true;
-}
-
-bool
-TabChild::GetCachedFileDescriptor(const nsAString& aPath,
-                                  nsICachedFileDescriptorListener* aCallback)
-{
-    MOZ_ASSERT(NS_IsMainThread());
-    MOZ_ASSERT(!aPath.IsEmpty());
-    MOZ_ASSERT(aCallback);
-
-    // First see if we've already received a cached file descriptor for this
-    // path.
-    const CachedFileDescriptorInfo search(aPath);
-    uint32_t index =
-        mCachedFileDescriptorInfos.IndexOf(search, 0,
-                                           search.PathOnlyComparator());
-    if (index == mCachedFileDescriptorInfos.NoIndex) {
-        // We haven't received a file descriptor for this path yet. Assume that
-        // we will in a little while and save the request here.
-        mCachedFileDescriptorInfos.AppendElement(
-            new CachedFileDescriptorInfo(aPath, aCallback));
-        return false;
-    }
-
-    nsAutoPtr<CachedFileDescriptorInfo>& info =
-        mCachedFileDescriptorInfos[index];
-
-    MOZ_ASSERT(info);
-    MOZ_ASSERT(info->mPath == aPath);
-    MOZ_ASSERT(!info->mCallback);
-    MOZ_ASSERT(!info->mCanceled);
-
-    info->mCallback = aCallback;
-
-    nsRefPtr<CachedFileDescriptorCallbackRunnable> runnable =
-        new CachedFileDescriptorCallbackRunnable(info);
-    runnable->Dispatch();
-
-    mCachedFileDescriptorInfos.RemoveElementAt(index);
-    return true;
-}
-
-void
-TabChild::CancelCachedFileDescriptorCallback(
-                                     const nsAString& aPath,
-                                     nsICachedFileDescriptorListener* aCallback)
-{
-    MOZ_ASSERT(NS_IsMainThread());
-    MOZ_ASSERT(!aPath.IsEmpty());
-    MOZ_ASSERT(aCallback);
-
-    const CachedFileDescriptorInfo search(aPath, aCallback);
-    uint32_t index =
-        mCachedFileDescriptorInfos.IndexOf(search, 0,
-                                           search.PathAndCallbackComparator());
-    if (index == mCachedFileDescriptorInfos.NoIndex) {
-        // Nothing to do here.
-        return;
-    }
-
-    nsAutoPtr<CachedFileDescriptorInfo>& info =
-        mCachedFileDescriptorInfos[index];
-
-    MOZ_ASSERT(info);
-    MOZ_ASSERT(info->mPath == aPath);
-    MOZ_ASSERT(!info->mFileDescriptor.IsValid());
-    MOZ_ASSERT(info->mCallback == aCallback);
-    MOZ_ASSERT(!info->mCanceled);
-
-    // Set this flag so that we will close the file descriptor when it arrives.
-    info->mCanceled = true;
-}
-
 void
 TabChild::DoFakeShow()
 {
   RecvShow(nsIntSize(0, 0));
   mDidFakeShow = true;
 }
 
 bool

--- a/dom/ipc/TabChild.h
+++ b/dom/ipc/TabChild.h
@@ -49,17 +49,16 @@
 #include "nsWeakReference.h"
 #include "nsITabChild.h"
 #include "mozilla/Attributes.h"
 #include "FrameMetrics.h"
 #include "ProcessUtils.h"
 #include "mozilla/dom/TabContext.h"
 
 struct gfxMatrix;
-class nsICachedFileDescriptorListener;
 
 namespace mozilla {
 namespace layout {
 class RenderFrameChild;
 }
 
 namespace dom {
 
@@ -192,19 +191,16 @@ public:
      */
     virtual bool DoSendSyncMessage(const nsAString& aMessage,
                                    const mozilla::dom::StructuredCloneData& aData,
                                    InfallibleTArray<nsString>* aJSONRetVal);
     virtual bool DoSendAsyncMessage(const nsAString& aMessage,
                                     const mozilla::dom::StructuredCloneData& aData);
 
     virtual bool RecvLoadURL(const nsCString& uri);
-    virtual bool RecvCacheFileDescriptor(const nsString& aPath,
-                                         const FileDescriptor& aFileDescriptor)
-                                         MOZ_OVERRIDE;
     virtual bool RecvShow(const nsIntSize& size);
     virtual bool RecvUpdateDimensions(const nsRect& rect, const nsIntSize& size, const ScreenOrientation& orientation);
     virtual bool RecvUpdateFrame(const mozilla::layers::FrameMetrics& aFrameMetrics);
     virtual bool RecvHandleDoubleTap(const nsIntPoint& aPoint);
     virtual bool RecvHandleSingleTap(const nsIntPoint& aPoint);
     virtual bool RecvHandleLongTap(const nsIntPoint& aPoint);
     virtual bool RecvActivate();
     virtual bool RecvDeactivate();
@@ -316,25 +312,16 @@ public:
     /**
      * Get this object's app type.
      *
      * A TabChild's app type corresponds to the value of its frame element's
      * "mozapptype" attribute.
      */
     void GetAppType(nsAString& aAppType) const { aAppType = mAppType; }
 
-    // Returns true if the file descriptor was found in the cache, false
-    // otherwise.
-    bool GetCachedFileDescriptor(const nsAString& aPath,
-                                 nsICachedFileDescriptorListener* aCallback);
-
-    void CancelCachedFileDescriptorCallback(
-                                    const nsAString& aPath,
-                                    nsICachedFileDescriptorListener* aCallback);
-
 protected:
     virtual PRenderFrameChild* AllocPRenderFrame(ScrollingBehavior* aScrolling,
                                                  LayersBackend* aBackend,
                                                  int32_t* aMaxTextureSize,
                                                  uint64_t* aLayersId) MOZ_OVERRIDE;
     virtual bool DeallocPRenderFrame(PRenderFrameChild* aFrame) MOZ_OVERRIDE;
     virtual bool RecvDestroy() MOZ_OVERRIDE;
 
@@ -420,19 +407,16 @@ private:
 
     nsIDOMWindowUtils* GetDOMWindowUtils()
     {
         nsCOMPtr<nsPIDOMWindow> window = do_GetInterface(mWebNav);
         nsCOMPtr<nsIDOMWindowUtils> utils = do_GetInterface(window);
         return utils;
     }
 
-    class CachedFileDescriptorInfo;
-    class CachedFileDescriptorCallbackRunnable;
-
     nsCOMPtr<nsIWebNavigation> mWebNav;
     nsCOMPtr<nsIWidget> mWidget;
     nsCOMPtr<nsIURI> mLastURI;
     FrameMetrics mLastMetrics;
     RenderFrameChild* mRemoteFrame;
     nsRefPtr<TabChildGlobal> mTabChildGlobal;
     uint32_t mChromeFlags;
     nsIntRect mOuterRect;
@@ -441,19 +425,16 @@ private:
     // point of the touchstart.
     nsIntPoint mGestureDownPoint;
     // The touch identifier of the active gesture.
     int32_t mActivePointerId;
     // A timer task that fires if the tap-hold timeout is exceeded by
     // the touch we're tracking.  That is, if touchend or a touchmove
     // that exceeds the gesture threshold doesn't happen.
     CancelableTask* mTapHoldTimer;
-    // At present only 1 of these is really expected.
-    nsAutoTArray<nsAutoPtr<CachedFileDescriptorInfo>, 1>
-        mCachedFileDescriptorInfos;
     float mOldViewportWidth;
     nscolor mLastBackgroundColor;
     ScrollingBehavior mScrolling;
     bool mDidFakeShow;
     bool mNotified;
     bool mContentDocumentIsDisplayed;
     bool mTriedBrowserInit;
     nsString mAppType;

--- a/dom/ipc/TabParent.cpp
+++ b/dom/ipc/TabParent.cpp
@@ -45,143 +45,32 @@
 #include "nsIWidget.h"
 #include "nsIWindowWatcher.h"
 #include "nsNetUtil.h"
 #include "nsPIDOMWindow.h"
 #include "nsPrintfCString.h"
 #include "nsSerializationHelper.h"
 #include "nsServiceManagerUtils.h"
 #include "nsThreadUtils.h"
-#include "private/pprio.h"
 #include "StructuredCloneUtils.h"
 #include "TabChild.h"
 #include <algorithm>
 
 using namespace mozilla::dom;
 using namespace mozilla::ipc;
 using namespace mozilla::layers;
 using namespace mozilla::layout;
 using namespace mozilla::services;
 using namespace mozilla::widget;
 using namespace mozilla::dom::indexedDB;
 
 // The flags passed by the webProgress notifications are 16 bits shifted
 // from the ones registered by webProgressListeners.
 #define NOTIFY_FLAG_SHIFT 16
 
-class OpenFileAndSendFDRunnable : public nsRunnable
-{
-    const nsString mPath;
-    nsRefPtr<TabParent> mTabParent;
-    nsCOMPtr<nsIEventTarget> mEventTarget;
-    PRFileDesc* mFD;
-
-public:
-    OpenFileAndSendFDRunnable(const nsAString& aPath, TabParent* aTabParent)
-      : mPath(aPath), mTabParent(aTabParent), mFD(nullptr)
-    {
-        MOZ_ASSERT(NS_IsMainThread());
-        MOZ_ASSERT(!aPath.IsEmpty());
-        MOZ_ASSERT(aTabParent);
-    }
-
-    void Dispatch()
-    {
-        MOZ_ASSERT(NS_IsMainThread());
-
-        mEventTarget = do_GetService(NS_STREAMTRANSPORTSERVICE_CONTRACTID);
-        NS_ENSURE_TRUE_VOID(mEventTarget);
-
-        nsresult rv = mEventTarget->Dispatch(this, NS_DISPATCH_NORMAL);
-        NS_ENSURE_SUCCESS_VOID(rv);
-    }
-
-private:
-    ~OpenFileAndSendFDRunnable()
-    {
-        MOZ_ASSERT(!mFD);
-    }
-
-    // This shouldn't be called directly except by the event loop. Use Dispatch
-    // to start the sequence.
-    NS_IMETHOD Run()
-    {
-        if (NS_IsMainThread()) {
-            SendResponse();
-        } else if (mFD) {
-            CloseFile();
-        } else {
-            OpenFile();
-        }
-
-        return NS_OK;
-    }
-
-    void SendResponse()
-    {
-        MOZ_ASSERT(NS_IsMainThread());
-        MOZ_ASSERT(mTabParent);
-        MOZ_ASSERT(mEventTarget);
-        MOZ_ASSERT(mFD);
-
-        nsRefPtr<TabParent> tabParent;
-        mTabParent.swap(tabParent);
-
-        FileDescriptor::PlatformHandleType handle =
-            FileDescriptor::PlatformHandleType(PR_FileDesc2NativeHandle(mFD));
-
-        mozilla::unused << tabParent->SendCacheFileDescriptor(mPath, handle);
-
-        nsCOMPtr<nsIEventTarget> eventTarget;
-        mEventTarget.swap(eventTarget);
-
-        if (NS_FAILED(eventTarget->Dispatch(this, NS_DISPATCH_NORMAL))) {
-            NS_WARNING("Failed to dispatch to stream transport service!");
-
-            // It's probably safer to take the main thread IO hit here rather
-            // than leak a file descriptor.
-            CloseFile();
-        }
-    }
-
-    void OpenFile()
-    {
-        MOZ_ASSERT(!NS_IsMainThread());
-        MOZ_ASSERT(!mFD);
-
-        nsCOMPtr<nsIFile> file;
-        nsresult rv = NS_NewLocalFile(mPath, false, getter_AddRefs(file));
-        NS_ENSURE_SUCCESS_VOID(rv);
-
-        PRFileDesc* fd;
-        rv = file->OpenNSPRFileDesc(PR_RDONLY, 0, &fd);
-        NS_ENSURE_SUCCESS_VOID(rv);
-
-        mFD = fd;
-
-        if (NS_FAILED(NS_DispatchToMainThread(this, NS_DISPATCH_NORMAL))) {
-            NS_WARNING("Failed to dispatch to main thread!");
-
-            CloseFile();
-        }
-    }
-
-    void CloseFile()
-    {
-        // It's possible for this to happen on the main thread if the dispatch
-        // to the stream service fails after we've already opened the file so
-        // we can't assert the thread we're running on.
-
-        MOZ_ASSERT(mFD);
-
-        PR_Close(mFD);
-        mFD = nullptr;
-    }
-};
-
 namespace mozilla {
 namespace dom {
 
 TabParent* sEventCapturer;
 
 TabParent *TabParent::mIMETabParent = nullptr;
 
 NS_IMPL_ISUPPORTS3(TabParent, nsITabParent, nsIAuthPromptProvider, nsISecureBrowserUI)
@@ -199,17 +88,16 @@ TabParent::TabParent(const TabContext& a
   , mRect(0, 0, 0, 0)
   , mDimensions(0, 0)
   , mOrientation(0)
   , mDPI(0)
   , mShown(false)
   , mUpdatedDimensions(false)
   , mMarkedDestroying(false)
   , mIsDestroyed(false)
-  , mAppPackageFileDescriptorSent(false)
 {
 }
 
 TabParent::~TabParent()
 {
 }
 
 void
@@ -337,76 +225,33 @@ TabParent::AnswerCreateWindow(PBrowserPa
 
     *retval = frameLoader->GetRemoteBrowser();
     return true;
 }
 
 void
 TabParent::LoadURL(nsIURI* aURI)
 {
-    MOZ_ASSERT(aURI);
-
     if (mIsDestroyed) {
-        return;
+      return;
+    }
+    if (!mShown) {
+      nsAutoCString spec;
+      if (aURI) {
+        aURI->GetSpec(spec);
+      }
+      NS_WARNING(nsPrintfCString("TabParent::LoadURL(%s) called before "
+                                 "Show(). Ignoring LoadURL.\n", spec.get()).get());
+      return;
     }
 
     nsCString spec;
     aURI->GetSpec(spec);
 
-    if (!mShown) {
-        NS_WARNING(nsPrintfCString("TabParent::LoadURL(%s) called before "
-                                   "Show(). Ignoring LoadURL.\n",
-                                   spec.get()).get());
-        return;
-    }
-
     unused << SendLoadURL(spec);
-
-    // If this app is a packaged app then we can speed startup by sending over
-    // the file descriptor for the "application.zip" file that it will
-    // invariably request. Only do this once.
-    if (!mAppPackageFileDescriptorSent) {
-        mAppPackageFileDescriptorSent = true;
-
-        nsCOMPtr<mozIApplication> app = GetOwnOrContainingApp();
-        if (app) {
-            nsString manifestURL;
-            nsresult rv = app->GetManifestURL(manifestURL);
-            NS_ENSURE_SUCCESS_VOID(rv);
-
-            if (StringBeginsWith(manifestURL, NS_LITERAL_STRING("app:"))) {
-                nsString basePath;
-                rv = app->GetBasePath(basePath);
-                NS_ENSURE_SUCCESS_VOID(rv);
-
-                nsString appId;
-                rv = app->GetId(appId);
-                NS_ENSURE_SUCCESS_VOID(rv);
-
-                nsCOMPtr<nsIFile> packageFile;
-                rv = NS_NewLocalFile(basePath, false,
-                                     getter_AddRefs(packageFile));
-                NS_ENSURE_SUCCESS_VOID(rv);
-
-                rv = packageFile->Append(appId);
-                NS_ENSURE_SUCCESS_VOID(rv);
-
-                rv = packageFile->Append(NS_LITERAL_STRING("application.zip"));
-                NS_ENSURE_SUCCESS_VOID(rv);
-
-                nsString path;
-                rv = packageFile->GetPath(path);
-                NS_ENSURE_SUCCESS_VOID(rv);
-
-                nsRefPtr<OpenFileAndSendFDRunnable> openFileRunnable =
-                    new OpenFileAndSendFDRunnable(path, this);
-                openFileRunnable->Dispatch();
-            }
-        }
-    }
 }
 
 void
 TabParent::Show(const nsIntSize& size)
 {
     // sigh
     mShown = true;
     mDimensions = size;

--- a/dom/ipc/TabParent.h
+++ b/dom/ipc/TabParent.h
@@ -299,16 +299,14 @@ private:
     void MaybeForwardEventToRenderFrame(const nsInputEvent& aEvent,
                                         nsInputEvent* aOutEvent);
     // When true, we've initiated normal shutdown and notified our
     // managing PContent.
     bool mMarkedDestroying;
     // When true, the TabParent is invalid and we should not send IPC messages
     // anymore.
     bool mIsDestroyed;
-    // Whether we have already sent a FileDescriptor for the app package.
-    bool mAppPackageFileDescriptorSent;
 };
 
 } // namespace dom
 } // namespace mozilla
 
 #endif

deleted file mode 100644
--- a/dom/ipc/nsICachedFileDescriptorListener.h
+++ /dev/null
@@ -1,38 +0,0 @@
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this file,
- * You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-#ifndef mozilla_dom_ipc_nsICachedFileDescriptorListener_h
-#define mozilla_dom_ipc_nsICachedFileDescriptorListener_h
-
-#include "nsISupports.h"
-
-#ifndef NS_NO_VTABLE
-#define NS_NO_VTABLE
-#endif
-
-#define NS_ICACHEDFILEDESCRIPTORLISTENER_IID \
-  {0x2cedaee0, 0x6ef2, 0x4f60, {0x9a, 0x6c, 0xdf, 0x4e, 0x4d, 0x65, 0x6a, 0xf7}}
-
-class nsAString;
-
-namespace mozilla {
-namespace ipc {
-class FileDescriptor;
-}
-}
-
-class NS_NO_VTABLE nsICachedFileDescriptorListener : public nsISupports
-{
-public:
-  NS_DECLARE_STATIC_IID_ACCESSOR(NS_ICACHEDFILEDESCRIPTORLISTENER_IID)
-
-  virtual void
-  OnCachedFileDescriptor(const nsAString& aPath,
-                         const mozilla::ipc::FileDescriptor& aFD) = 0;
-};
-
-NS_DEFINE_STATIC_IID_ACCESSOR(nsICachedFileDescriptorListener,
-                              NS_ICACHEDFILEDESCRIPTORLISTENER_IID)
-
-#endif // mozilla_dom_ipc_nsICachedFileDescriptorListener_h

--- a/ipc/glue/FileDescriptor.cpp
+++ b/ipc/glue/FileDescriptor.cpp
@@ -37,18 +37,17 @@ FileDescriptor::FileDescriptor(PlatformH
   mHandleCreatedByOtherProcessWasUsed(false)
 {
   DuplicateInCurrentProcess(aHandle);
 }
 
 void
 FileDescriptor::DuplicateInCurrentProcess(PlatformHandleType aHandle)
 {
-  MOZ_ASSERT_IF(mHandleCreatedByOtherProcess,
-                mHandleCreatedByOtherProcessWasUsed);
+  MOZ_ASSERT(!mHandleCreatedByOtherProcess);
 
   if (IsValid(aHandle)) {
     PlatformHandleType newHandle;
 #ifdef XP_WIN
     if (DuplicateHandle(GetCurrentProcess(), aHandle, GetCurrentProcess(),
                         &newHandle, 0, FALSE, DUPLICATE_SAME_ACCESS)) {
 #else // XP_WIN
     if ((newHandle = dup(aHandle)) != INVALID_HANDLE) {

--- a/ipc/glue/FileDescriptor.h
+++ b/ipc/glue/FileDescriptor.h
@@ -48,19 +48,17 @@ public:
   // This should only ever be created by IPDL.
   struct IPDLPrivate
   {};
 
   FileDescriptor();
 
   FileDescriptor(const FileDescriptor& aOther)
   {
-    // Don't use operator= here because that will call
-    // CloseCurrentProcessHandle() on this (uninitialized) object.
-    Assign(aOther);
+    *this = aOther;
   }
 
   FileDescriptor(PlatformHandleType aHandle);
 
   FileDescriptor(const IPDLPrivate&, const PickleType& aPickle)
 #ifdef XP_WIN
   : mHandle(aPickle)
 #else
@@ -74,17 +72,28 @@ public:
   {
     CloseCurrentProcessHandle();
   }
 
   FileDescriptor&
   operator=(const FileDescriptor& aOther)
   {
     CloseCurrentProcessHandle();
-    Assign(aOther);
+
+    if (aOther.mHandleCreatedByOtherProcess) {
+      mHandleCreatedByOtherProcess = true;
+      mHandleCreatedByOtherProcessWasUsed =
+        aOther.mHandleCreatedByOtherProcessWasUsed;
+      mHandle = aOther.PlatformHandle();
+    } else {
+      DuplicateInCurrentProcess(aOther.PlatformHandle());
+      mHandleCreatedByOtherProcess = false;
+      mHandleCreatedByOtherProcessWasUsed = false;
+    }
+
     return *this;
   }
 
   // Performs platform-specific actions to duplicate mHandle in the other
   // process (e.g. dup() on POSIX, DuplicateHandle() on Windows). Returns a
   // pickled value that can be passed to the other process via IPC.
   PickleType
   ShareTo(const IPDLPrivate&, ProcessHandle aOtherProcess) const;
@@ -108,31 +117,16 @@ public:
 
   bool
   operator==(const FileDescriptor& aOther) const
   {
     return mHandle == aOther.mHandle;
   }
 
 private:
-  void
-  Assign(const FileDescriptor& aOther)
-  {
-    if (aOther.mHandleCreatedByOtherProcess) {
-      mHandleCreatedByOtherProcess = true;
-      mHandleCreatedByOtherProcessWasUsed =
-        aOther.mHandleCreatedByOtherProcessWasUsed;
-      mHandle = aOther.PlatformHandle();
-    } else {
-      DuplicateInCurrentProcess(aOther.PlatformHandle());
-      mHandleCreatedByOtherProcess = false;
-      mHandleCreatedByOtherProcessWasUsed = false;
-    }
-  }
-
   static bool
   IsValid(PlatformHandleType aHandle);
 
   void
   DuplicateInCurrentProcess(PlatformHandleType aHandle);
 
   void
   CloseCurrentProcessHandle();

deleted file mode 100644
--- a/ipc/glue/FileDescriptorUtils.cpp
+++ /dev/null
@@ -1,81 +0,0 @@
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-#include "FileDescriptorUtils.h"
-
-#include "nsIEventTarget.h"
-
-#include "nsCOMPtr.h"
-#include "nsDebug.h"
-#include "nsNetCID.h"
-#include "nsServiceManagerUtils.h"
-#include "nsThreadUtils.h"
-#include "prio.h"
-#include "private/pprio.h"
-
-using mozilla::ipc::CloseFileRunnable;
-
-#ifdef DEBUG
-
-CloseFileRunnable::CloseFileRunnable(const FileDescriptor& aFileDescriptor)
-: mFileDescriptor(aFileDescriptor)
-{
-  MOZ_ASSERT(NS_IsMainThread());
-  MOZ_ASSERT(aFileDescriptor.IsValid());
-}
-
-#endif // DEBUG
-
-CloseFileRunnable::~CloseFileRunnable()
-{
-  if (mFileDescriptor.IsValid()) {
-    // It's probably safer to take the main thread IO hit here rather than leak
-    // the file descriptor.
-    CloseFile();
-  }
-}
-
-NS_IMPL_THREADSAFE_ISUPPORTS1(CloseFileRunnable, nsIRunnable)
-
-void
-CloseFileRunnable::Dispatch()
-{
-  MOZ_ASSERT(NS_IsMainThread());
-
-  nsCOMPtr<nsIEventTarget> eventTarget =
-    do_GetService(NS_STREAMTRANSPORTSERVICE_CONTRACTID);
-  NS_ENSURE_TRUE_VOID(eventTarget);
-
-  nsresult rv = eventTarget->Dispatch(this, NS_DISPATCH_NORMAL);
-  NS_ENSURE_SUCCESS_VOID(rv);
-}
-
-void
-CloseFileRunnable::CloseFile()
-{
-  // It's possible for this to happen on the main thread if the dispatch to the
-  // stream service fails so we can't assert the thread on which we're running.
-
-  MOZ_ASSERT(mFileDescriptor.IsValid());
-
-  PRFileDesc* fd =
-    PR_ImportFile(PROsfd(mFileDescriptor.PlatformHandle()));
-  NS_WARN_IF_FALSE(fd, "Failed to import file handle!");
-
-  mFileDescriptor = FileDescriptor();
-
-  if (fd) {
-    PR_Close(fd);
-    fd = nullptr;
-  }
-}
-
-NS_IMETHODIMP
-CloseFileRunnable::Run()
-{
-  MOZ_ASSERT(!NS_IsMainThread());
-
-  CloseFile();
-  return NS_OK;
-}

deleted file mode 100644
--- a/ipc/glue/FileDescriptorUtils.h
+++ /dev/null
@@ -1,47 +0,0 @@
-
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-#ifndef mozilla_ipc_FileDescriptorUtils_h
-#define mozilla_ipc_FileDescriptorUtils_h
-
-#include "mozilla/ipc/FileDescriptor.h"
-#include "nsIRunnable.h"
-
-namespace mozilla {
-namespace ipc {
-
-// When Dispatch() is called (from main thread) this class arranges to close the
-// provided FileDescriptor on one of the socket transport service threads (to
-// avoid main thread I/O).
-class CloseFileRunnable : public nsIRunnable
-{
-  typedef mozilla::ipc::FileDescriptor FileDescriptor;
-
-  FileDescriptor mFileDescriptor;
-
-public:
-  CloseFileRunnable(const FileDescriptor& aFileDescriptor)
-#ifdef DEBUG
-  ;
-#else
-  : mFileDescriptor(aFileDescriptor)
-  { }
-#endif
-
-  NS_DECL_ISUPPORTS
-  NS_DECL_NSIRUNNABLE
-
-  void Dispatch();
-
-private:
-  ~CloseFileRunnable();
-
-  void CloseFile();
-};
-
-} // namespace ipc
-} // namespace mozilla
-
-#endif // mozilla_ipc_FileDescriptorUtils_h

--- a/ipc/glue/Makefile.in
+++ b/ipc/glue/Makefile.in
@@ -21,17 +21,16 @@ EXPORTS_NAMESPACES = ipc mozilla/ipc
 
 EXPORTS_ipc = IPCMessageUtils.h
 
 EXPORTS_mozilla/ipc = \
   AsyncChannel.h \
   BrowserProcessSubThread.h \
   CrossProcessMutex.h \
   FileDescriptor.h \
-  FileDescriptorUtils.h \
   GeckoChildProcessHost.h \
   InputStreamUtils.h \
   IOThreadChild.h \
   ProcessChild.h \
   ProtocolUtils.h \
   RPCChannel.h \
   SharedMemory.h \
   SharedMemoryBasic.h \
@@ -67,17 +66,16 @@ EXPORTS_mozilla/ipc += SharedMemoryBasic
 else
 EXPORTS_mozilla/ipc += SharedMemoryBasic_chromium.h
 endif #}
 
 CPPSRCS += \
   AsyncChannel.cpp \
   BrowserProcessSubThread.cpp \
   FileDescriptor.cpp \
-  FileDescriptorUtils.cpp \
   GeckoChildProcessHost.cpp \
   InputStreamUtils.cpp \
   MessagePump.cpp \
   ProcessChild.cpp \
   ProtocolUtils.cpp \
   RPCChannel.cpp \
   ScopedXREEmbed.cpp \
   SharedMemory.cpp \

--- a/modules/libjar/nsJARChannel.cpp
+++ b/modules/libjar/nsJARChannel.cpp
@@ -13,16 +13,17 @@
 #include "nsIPrefService.h"
 #include "nsIPrefBranch.h"
 #include "nsIViewSourceChannel.h"
 #include "nsChannelProperties.h"
 
 #include "nsIScriptSecurityManager.h"
 #include "nsIPrincipal.h"
 #include "nsIFileURL.h"
+#include "nsXULAppAPI.h"
 
 #include "mozilla/Preferences.h"
 #include "mozilla/net/RemoteOpenFileChild.h"
 #include "nsITabChild.h"
 
 using namespace mozilla;
 using namespace mozilla::net;
 
@@ -343,19 +344,19 @@ nsJARChannel::LookupFile()
     // try to get a nsIFile directly from the url, which will often succeed.
     {
         nsCOMPtr<nsIFileURL> fileURL = do_QueryInterface(mJarBaseURI);
         if (fileURL)
             fileURL->GetFile(getter_AddRefs(mJarFile));
     }
     // if we're in child process and have special "remoteopenfile:://" scheme,
     // create special nsIFile that gets file handle from parent when opened.
-    if (!mJarFile && !gJarHandler->IsMainProcess()) {
+    if (!mJarFile && XRE_GetProcessType() != GeckoProcessType_Default) {
         nsAutoCString scheme;
-        rv = mJarBaseURI->GetScheme(scheme);
+        nsresult rv = mJarBaseURI->GetScheme(scheme);
         if (NS_SUCCEEDED(rv) && scheme.EqualsLiteral("remoteopenfile")) {
             nsRefPtr<RemoteOpenFileChild> remoteFile = new RemoteOpenFileChild();
             rv = remoteFile->Init(mJarBaseURI);
             NS_ENSURE_SUCCESS(rv, rv);
             mJarFile = remoteFile;
 
             nsIZipReaderCache *jarCache = gJarHandler->JarCache();
             if (jarCache) {
@@ -363,30 +364,23 @@ nsJARChannel::LookupFile()
                 rv = jarCache->IsCached(mJarFile, &cached);
                 if (NS_SUCCEEDED(rv) && cached) {
                     // zipcache already has file mmapped: don't open on parent,
                     // just return and proceed to cache hit in CreateJarInput()
                     return NS_OK;
                 }
             }
 
-            mOpeningRemote = true;
-
-            if (gJarHandler->RemoteOpenFileInProgress(remoteFile, this)) {
-                // JarHandler will trigger OnRemoteFileOpen() after the first
-                // request for this file completes and we'll get a JAR cache
-                // hit.
-                return NS_OK;
-            }
-
             // Open file on parent: OnRemoteFileOpenComplete called when done
             nsCOMPtr<nsITabChild> tabChild;
             NS_QueryNotificationCallbacks(mCallbacks, mLoadGroup, tabChild);
             rv = remoteFile->AsyncRemoteFileOpen(PR_RDONLY, this, tabChild.get());
             NS_ENSURE_SUCCESS(rv, rv);
+
+            mOpeningRemote = true;
         }
     }
     // try to handle a nested jar
     if (!mJarFile) {
         nsCOMPtr<nsIJARURI> jarURI = do_QueryInterface(mJarBaseURI);
         if (jarURI) {
             nsCOMPtr<nsIFileURL> fileURL;
             nsCOMPtr<nsIURI> innerJarURI;
@@ -398,48 +392,16 @@ nsJARChannel::LookupFile()
                 jarURI->GetJAREntry(mInnerJarEntry);
             }
         }
     }
 
     return rv;
 }
 
-nsresult
-nsJARChannel::OpenLocalFile()
-{
-    MOZ_ASSERT(mIsPending);
-
-    // Local files are always considered safe.
-    mIsUnsafe = false;
-
-    nsRefPtr<nsJARInputThunk> input;
-    nsresult rv = CreateJarInput(gJarHandler->JarCache(),
-                                 getter_AddRefs(input));
-    if (NS_SUCCEEDED(rv)) {
-        // Create input stream pump and call AsyncRead as a block.
-        rv = NS_NewInputStreamPump(getter_AddRefs(mPump), input);
-        if (NS_SUCCEEDED(rv))
-            rv = mPump->AsyncRead(this, nullptr);
-    }
-
-    return rv;
-}
-
-void
-nsJARChannel::NotifyError(nsresult aError)
-{
-    MOZ_ASSERT(NS_FAILED(aError));
-
-    mStatus = aError;
-
-    OnStartRequest(nullptr, nullptr);
-    OnStopRequest(nullptr, nullptr, aError);
-}
-
 //-----------------------------------------------------------------------------
 // nsIRequest
 //-----------------------------------------------------------------------------
 
 NS_IMETHODIMP
 nsJARChannel::GetName(nsACString &result)
 {
     return mJarURI->GetSpec(result);
@@ -782,17 +744,27 @@ nsJARChannel::AsyncOpen(nsIStreamListene
         rv = NS_NewDownloader(getter_AddRefs(mDownloader), this);
         if (NS_SUCCEEDED(rv))
             rv = NS_OpenURI(mDownloader, nullptr, mJarBaseURI, nullptr,
                             mLoadGroup, mCallbacks,
                             mLoadFlags & ~(LOAD_DOCUMENT_URI | LOAD_CALL_CONTENT_SNIFFERS));
     } else if (mOpeningRemote) {
         // nothing to do: already asked parent to open file.
     } else {
-        rv = OpenLocalFile();
+        // local files are always considered safe
+        mIsUnsafe = false;
+
+        nsRefPtr<nsJARInputThunk> input;
+        rv = CreateJarInput(gJarHandler->JarCache(), getter_AddRefs(input));
+        if (NS_SUCCEEDED(rv)) {
+            // create input stream pump and call AsyncRead as a block
+            rv = NS_NewInputStreamPump(getter_AddRefs(mPump), input);
+            if (NS_SUCCEEDED(rv))
+                rv = mPump->AsyncRead(this, nullptr);
+        }
     }
 
     if (NS_FAILED(rv)) {
         mIsPending = false;
         mListenerContext = nullptr;
         mListener = nullptr;
         return rv;
     }
@@ -925,43 +897,56 @@ nsJARChannel::OnDownloadComplete(nsIDown
             rv = NS_NewInputStreamPump(getter_AddRefs(mPump), input);
             if (NS_SUCCEEDED(rv))
                 rv = mPump->AsyncRead(this, nullptr);
         }
         status = rv;
     }
 
     if (NS_FAILED(status)) {
-        NotifyError(status);
+        mStatus = status;
+        OnStartRequest(nullptr, nullptr);
+        OnStopRequest(nullptr, nullptr, status);
     }
 
     return NS_OK;
 }
 
 //-----------------------------------------------------------------------------
 // nsIRemoteOpenFileListener
 //-----------------------------------------------------------------------------
 nsresult
 nsJARChannel::OnRemoteFileOpenComplete(nsresult aOpenStatus)
 {
     nsresult rv = aOpenStatus;
 
-    // NS_ERROR_ALREADY_OPENED here means we'll hit JAR cache in
-    // OpenLocalFile().
-    if (NS_SUCCEEDED(rv) || rv == NS_ERROR_ALREADY_OPENED) {
-        rv = OpenLocalFile();
+    if (NS_SUCCEEDED(rv)) {
+        // files on parent are always considered safe
+        mIsUnsafe = false;
+
+        nsRefPtr<nsJARInputThunk> input;
+        rv = CreateJarInput(gJarHandler->JarCache(), getter_AddRefs(input));
+        if (NS_SUCCEEDED(rv)) {
+            // create input stream pump and call AsyncRead as a block
+            rv = NS_NewInputStreamPump(getter_AddRefs(mPump), input);
+            if (NS_SUCCEEDED(rv))
+                rv = mPump->AsyncRead(this, nullptr);
+        }
     }
 
     if (NS_FAILED(rv)) {
-        NotifyError(rv);
+        mStatus = rv;
+        OnStartRequest(nullptr, nullptr);
+        OnStopRequest(nullptr, nullptr, mStatus);
     }
 
     return NS_OK;
 }
 
+
 //-----------------------------------------------------------------------------
 // nsIStreamListener
 //-----------------------------------------------------------------------------
 
 NS_IMETHODIMP
 nsJARChannel::OnStartRequest(nsIRequest *req, nsISupports *ctx)
 {
     LOG(("nsJARChannel::OnStartRequest [this=%x %s]\n", this, mSpec.get()));

--- a/modules/libjar/nsJARChannel.h
+++ b/modules/libjar/nsJARChannel.h
@@ -46,18 +46,16 @@ public:
     nsJARChannel();
     virtual ~nsJARChannel();
 
     nsresult Init(nsIURI *uri);
 
 private:
     nsresult CreateJarInput(nsIZipReaderCache *, nsJARInputThunk **);
     nsresult LookupFile();
-    nsresult OpenLocalFile();
-    void NotifyError(nsresult aError);
 
 #if defined(PR_LOGGING)
     nsCString                       mSpec;
 #endif
 
     bool                            mOpened;
 
     nsCOMPtr<nsIJARURI>             mJarURI;

--- a/modules/libjar/nsJARProtocolHandler.cpp
+++ b/modules/libjar/nsJARProtocolHandler.cpp
@@ -12,37 +12,27 @@
 #include "nsJARURI.h"
 #include "nsIURL.h"
 #include "nsJARChannel.h"
 #include "nsXPIDLString.h"
 #include "nsString.h"
 #include "nsNetCID.h"
 #include "nsIMIMEService.h"
 #include "nsMimeTypes.h"
-#include "nsIRemoteOpenFileListener.h"
-#include "nsIHashable.h"
-#include "nsThreadUtils.h"
-#include "nsXULAppAPI.h"
 
 static NS_DEFINE_CID(kZipReaderCacheCID, NS_ZIPREADERCACHE_CID);
 
 #define NS_JAR_CACHE_SIZE 32
 
 //-----------------------------------------------------------------------------
 
 nsJARProtocolHandler *gJarHandler = nullptr;
 
 nsJARProtocolHandler::nsJARProtocolHandler()
-: mIsMainProcess(XRE_GetProcessType() == GeckoProcessType_Default)
 {
-    MOZ_ASSERT(NS_IsMainThread());
-
-    if (!mIsMainProcess) {
-        mRemoteFileListeners.Init();
-    }
 }
 
 nsJARProtocolHandler::~nsJARProtocolHandler()
 {
 }
 
 nsresult
 nsJARProtocolHandler::Init()
@@ -60,77 +50,16 @@ nsIMIMEService *
 nsJARProtocolHandler::MimeService()
 {
     if (!mMimeService)
         mMimeService = do_GetService("@mozilla.org/mime;1");
 
     return mMimeService.get();
 }
 
-bool
-nsJARProtocolHandler::RemoteOpenFileInProgress(
-                                           nsIHashable *aRemoteFile,
-                                           nsIRemoteOpenFileListener *aListener)
-{
-    MOZ_ASSERT(NS_IsMainThread());
-    MOZ_ASSERT(aRemoteFile);
-    MOZ_ASSERT(aListener);
-
-    if (IsMainProcess()) {
-        MOZ_NOT_REACHED("Shouldn't be called in the main process!");
-        return false;
-    }
-
-    RemoteFileListenerArray *listeners;
-    if (mRemoteFileListeners.Get(aRemoteFile, &listeners)) {
-        listeners->AppendElement(aListener);
-        return true;
-    }
-
-    // We deliberately don't put the listener in the new array since the first
-    // load is handled differently.
-    mRemoteFileListeners.Put(aRemoteFile, new RemoteFileListenerArray());
-    return false;
-}
-
-void
-nsJARProtocolHandler::RemoteOpenFileComplete(nsIHashable *aRemoteFile,
-                                             nsresult aStatus)
-{
-    MOZ_ASSERT(NS_IsMainThread());
-    MOZ_ASSERT(aRemoteFile);
-
-    if (IsMainProcess()) {
-        MOZ_NOT_REACHED("Shouldn't be called in the main process!");
-        return;
-    }
-
-    RemoteFileListenerArray *tempListeners;
-    if (!mRemoteFileListeners.Get(aRemoteFile, &tempListeners)) {
-        return;
-    }
-
-    // Save the listeners in a stack array. The call to Remove() below will
-    // delete the tempListeners array.
-    RemoteFileListenerArray listeners;
-    tempListeners->SwapElements(listeners);
-
-    mRemoteFileListeners.Remove(aRemoteFile);
-
-    // Technically we must fail OnRemoteFileComplete() since OpenNSPRFileDesc()
-    // won't succeed here. We've trained nsJARChannel to recognize
-    // NS_ERROR_ALREADY_OPENED in this case as "proceed to JAR cache hit."
-    nsresult status = NS_SUCCEEDED(aStatus) ? NS_ERROR_ALREADY_OPENED : aStatus;
-
-    uint32_t count = listeners.Length();
-    for (uint32_t index = 0; index < count; index++) {
-        listeners[index]->OnRemoteFileOpenComplete(status);
-    }
-}
-
 NS_IMPL_THREADSAFE_ISUPPORTS3(nsJARProtocolHandler,
                               nsIJARProtocolHandler,
                               nsIProtocolHandler,
                               nsISupportsWeakReference)
 
 nsJARProtocolHandler*
 nsJARProtocolHandler::GetSingleton()
 {

--- a/modules/libjar/nsJARProtocolHandler.h
+++ b/modules/libjar/nsJARProtocolHandler.h
@@ -8,28 +8,20 @@
 
 #include "nsIJARProtocolHandler.h"
 #include "nsIProtocolHandler.h"
 #include "nsIJARURI.h"
 #include "nsIZipReader.h"
 #include "nsIMIMEService.h"
 #include "nsWeakReference.h"
 #include "nsCOMPtr.h"
-#include "nsClassHashtable.h"
-#include "nsHashKeys.h"
-
-class nsIHashable;
-class nsIRemoteOpenFileListener;
 
 class nsJARProtocolHandler : public nsIJARProtocolHandler
                            , public nsSupportsWeakReference
 {
-    typedef nsAutoTArray<nsCOMPtr<nsIRemoteOpenFileListener>, 5>
-            RemoteFileListenerArray;
-
 public:
     NS_DECL_ISUPPORTS
     NS_DECL_NSIPROTOCOLHANDLER
     NS_DECL_NSIJARPROTOCOLHANDLER
 
     // nsJARProtocolHandler methods:
     nsJARProtocolHandler();
     virtual ~nsJARProtocolHandler();
@@ -37,32 +29,19 @@ public:
     static nsJARProtocolHandler *GetSingleton();
 
     nsresult Init();
 
     // returns non addref'ed pointer.  
     nsIMIMEService    *MimeService();
     nsIZipReaderCache *JarCache() { return mJARCache; }
 
-    bool IsMainProcess() const { return mIsMainProcess; }
-
-    bool RemoteOpenFileInProgress(nsIHashable *aRemoteFile,
-                                  nsIRemoteOpenFileListener *aListener);
-    void RemoteOpenFileComplete(nsIHashable *aRemoteFile, nsresult aStatus);
-
 protected:
     nsCOMPtr<nsIZipReaderCache> mJARCache;
     nsCOMPtr<nsIMIMEService> mMimeService;
-
-    // Holds lists of RemoteOpenFileChild (not including the 1st) that have
-    // requested the same file from parent.
-    nsClassHashtable<nsHashableHashKey, RemoteFileListenerArray>
-        mRemoteFileListeners;
-
-    bool mIsMainProcess;
 };
 
 extern nsJARProtocolHandler *gJarHandler;
 
 #define NS_JARPROTOCOLHANDLER_CLASSNAME \
     "nsJarProtocolHandler"
 #define NS_JARPROTOCOLHANDLER_CID                    \
 { /* 0xc7e410d4-0x85f2-11d3-9f63-006008a6efe9 */     \

--- a/netwerk/ipc/Makefile.in
+++ b/netwerk/ipc/Makefile.in
@@ -41,14 +41,13 @@ CPPSRCS =               \
   ChannelEventQueue.cpp \
   RemoteOpenFileParent.cpp \
   RemoteOpenFileChild.cpp  \
   $(NULL)
 
 LOCAL_INCLUDES +=                  \
   -I$(srcdir)/../protocol/http \
   -I$(srcdir)/../base/src          \
-  -I$(topsrcdir)/modules/libjar    \
   $(NULL)
 
 include $(topsrcdir)/config/config.mk
 include $(topsrcdir)/ipc/chromium/chromium-config.mk
 include $(topsrcdir)/config/rules.mk

--- a/netwerk/ipc/RemoteOpenFileChild.cpp
+++ b/netwerk/ipc/RemoteOpenFileChild.cpp
@@ -1,53 +1,44 @@
 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* vim: set sw=2 ts=8 et tw=80 : */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+#include "mozilla/net/NeckoChild.h"
 #include "mozilla/net/RemoteOpenFileChild.h"
-
-#include "mozilla/ipc/FileDescriptor.h"
-#include "mozilla/ipc/FileDescriptorUtils.h"
+#include "nsIRemoteOpenFileListener.h"
 #include "mozilla/ipc/URIUtils.h"
-#include "mozilla/net/NeckoChild.h"
-#include "nsJARProtocolHandler.h"
-#include "nsIRemoteOpenFileListener.h"
 
 // needed to alloc/free NSPR file descriptors
 #include "private/pprio.h"
 
 using namespace mozilla::ipc;
 
 namespace mozilla {
 namespace net {
 
-NS_IMPL_THREADSAFE_ISUPPORTS3(RemoteOpenFileChild,
+NS_IMPL_THREADSAFE_ISUPPORTS2(RemoteOpenFileChild,
                               nsIFile,
-                              nsIHashable,
-                              nsICachedFileDescriptorListener)
+                              nsIHashable)
+
 
 RemoteOpenFileChild::RemoteOpenFileChild(const RemoteOpenFileChild& other)
-  : mTabChild(other.mTabChild)
-  , mNSPRFileDesc(other.mNSPRFileDesc)
+  : mNSPRFileDesc(other.mNSPRFileDesc)
   , mAsyncOpenCalled(other.mAsyncOpenCalled)
   , mNSPROpenCalled(other.mNSPROpenCalled)
 {
   // Note: don't clone mListener or we'll have a refcount leak.
   other.mURI->Clone(getter_AddRefs(mURI));
   other.mFile->Clone(getter_AddRefs(mFile));
 }
 
 RemoteOpenFileChild::~RemoteOpenFileChild()
 {
-  if (mListener) {
-    NotifyListener(NS_ERROR_UNEXPECTED);
-  }
-
   if (mNSPRFileDesc) {
     // If we handed out fd we shouldn't have pointer to it any more.
     MOZ_ASSERT(!mNSPROpenCalled);
     // PR_Close both closes the file and deallocates the PRFileDesc
     PR_Close(mNSPRFileDesc);
   }
 }
 
@@ -106,178 +97,118 @@ RemoteOpenFileChild::AsyncRemoteFileOpen
   if (mAsyncOpenCalled) {
     return NS_ERROR_ALREADY_OPENED;
   }
 
   if (aFlags != PR_RDONLY) {
     return NS_ERROR_NOT_AVAILABLE;
   }
 
-  mTabChild = static_cast<TabChild*>(aTabChild);
-
-  if (MissingRequiredTabChild(mTabChild, "remoteopenfile")) {
+  mozilla::dom::TabChild* tabChild = nullptr;
+  if (aTabChild) {
+    tabChild = static_cast<mozilla::dom::TabChild*>(aTabChild);
+  }
+  if (MissingRequiredTabChild(tabChild, "remoteopenfile")) {
     return NS_ERROR_ILLEGAL_VALUE;
   }
 
 #if defined(XP_WIN) || defined(MOZ_WIDGET_COCOA)
   // Windows/OSX desktop builds skip remoting, and just open file in child
   // process when asked for NSPR handle
   aListener->OnRemoteFileOpenComplete(NS_OK);
   mAsyncOpenCalled = true;
   return NS_OK;
 #else
-  nsString path;
-  if (NS_FAILED(mFile->GetPath(path))) {
-    MOZ_NOT_REACHED("Couldn't get path from file!");
-  }
-
-  if (mTabChild) {
-    if (mTabChild->GetCachedFileDescriptor(path, this)) {
-      // The file descriptor was found in the cache and OnCachedFileDescriptor()
-      // will be called with it.
-      return NS_OK;
-    }
-  }
-
   URIParams uri;
   SerializeURI(mURI, uri);
 
-  gNeckoChild->SendPRemoteOpenFileConstructor(this, uri, mTabChild);
+  gNeckoChild->SendPRemoteOpenFileConstructor(this, uri, tabChild);
 
   // Can't seem to reply from within IPDL Parent constructor, so send open as
   // separate message
   SendAsyncOpenFile();
 
   // The chrome process now has a logical ref to us until we call Send__delete
   AddIPDLReference();
 
   mListener = aListener;
   mAsyncOpenCalled = true;
   return NS_OK;
 #endif
 }
 
-void
-RemoteOpenFileChild::OnCachedFileDescriptor(const nsAString& aPath,
-                                            const FileDescriptor& aFD)
-{
-#ifdef DEBUG
-  if (!aPath.IsEmpty()) {
-    MOZ_ASSERT(mFile);
-
-    nsString path;
-    if (NS_FAILED(mFile->GetPath(path))) {
-      MOZ_NOT_REACHED("Couldn't get path from file!");
-    }
-
-    MOZ_ASSERT(path == aPath, "Paths don't match!");
-  }
-#endif
-
-  HandleFileDescriptorAndNotifyListener(aFD, /* aFromRecvFileOpened */ false);
-}
-
-void
-RemoteOpenFileChild::HandleFileDescriptorAndNotifyListener(
-                                                      const FileDescriptor& aFD,
-                                                      bool aFromRecvFileOpened)
-{
-#if defined(XP_WIN) || defined(MOZ_WIDGET_COCOA)
-  MOZ_NOT_REACHED("OS X and Windows shouldn't be doing IPDL here");
-#else
-  if (!mListener) {
-    // We already notified our listener (either in response to a cached file
-    // descriptor callback or through the normal messaging mechanism). Close the
-    // file descriptor if it is valid.
-    if (aFD.IsValid()) {
-      nsRefPtr<CloseFileRunnable> runnable = new CloseFileRunnable(aFD);
-      runnable->Dispatch();
-    }
-    return;
-  }
-
-  MOZ_ASSERT(!mNSPRFileDesc);
-
-  nsRefPtr<TabChild> tabChild;
-  mTabChild.swap(tabChild);
-
-  // If there is a pending callback and we're being called from IPDL then we
-  // need to cancel it.
-  if (tabChild && aFromRecvFileOpened) {
-    nsString path;
-    if (NS_FAILED(mFile->GetPath(path))) {
-      MOZ_NOT_REACHED("Couldn't get path from file!");
-    }
-
-    tabChild->CancelCachedFileDescriptorCallback(path, this);
-  }
-
-  if (aFD.IsValid()) {
-    mNSPRFileDesc = PR_ImportFile(aFD.PlatformHandle());
-    if (!mNSPRFileDesc) {
-      NS_WARNING("Failed to import file handle!");
-    }
-  }
-
-  NotifyListener(mNSPRFileDesc ? NS_OK : NS_ERROR_FILE_NOT_FOUND);
-#endif
-}
-
-void
-RemoteOpenFileChild::NotifyListener(nsresult aResult)
-{
-  MOZ_ASSERT(mListener);
-  mListener->OnRemoteFileOpenComplete(aResult);
-  mListener = nullptr;     // release ref to listener
-
-  nsRefPtr<nsJARProtocolHandler> handler(gJarHandler);
-  NS_WARN_IF_FALSE(handler, "nsJARProtocolHandler is already gone!");
-
-  if (handler) {
-    handler->RemoteOpenFileComplete(this, aResult);
-  }
-}
 
 //-----------------------------------------------------------------------------
 // RemoteOpenFileChild::PRemoteOpenFileChild
 //-----------------------------------------------------------------------------
 
 bool
 RemoteOpenFileChild::RecvFileOpened(const FileDescriptor& aFD)
 {
 #if defined(XP_WIN) || defined(MOZ_WIDGET_COCOA)
-  NS_NOTREACHED("OS X and Windows shouldn't be doing IPDL here");
+  NS_NOTREACHED("osX and Windows shouldn't be doing IPDL here");
 #else
-  HandleFileDescriptorAndNotifyListener(aFD, /* aFromRecvFileOpened */ true);
+  if (!aFD.IsValid()) {
+    return RecvFileDidNotOpen();
+  }
+
+  MOZ_ASSERT(!mNSPRFileDesc);
+  mNSPRFileDesc = PR_AllocFileDesc(aFD.PlatformHandle(), PR_GetFileMethods());
+
+  MOZ_ASSERT(mListener);
+  mListener->OnRemoteFileOpenComplete(NS_OK);
+  mListener = nullptr;     // release ref to listener
 
   // This calls NeckoChild::DeallocPRemoteOpenFile(), which deletes |this| if
   // IPDL holds the last reference.  Don't rely on |this| existing after here!
   Send__delete__(this);
 #endif
 
   return true;
 }
 
 bool
 RemoteOpenFileChild::RecvFileDidNotOpen()
 {
 #if defined(XP_WIN) || defined(MOZ_WIDGET_COCOA)
-  NS_NOTREACHED("OS X and Windows shouldn't be doing IPDL here");
+  NS_NOTREACHED("osX and Windows shouldn't be doing IPDL here");
 #else
-  HandleFileDescriptorAndNotifyListener(FileDescriptor(),
-                                        /* aFromRecvFileOpened */ true);
+  MOZ_ASSERT(!mNSPRFileDesc);
+  printf_stderr("RemoteOpenFileChild: file was not opened!\n");
+
+  MOZ_ASSERT(mListener);
+  mListener->OnRemoteFileOpenComplete(NS_ERROR_FILE_NOT_FOUND);
+  mListener = nullptr;     // release ref to listener
 
   // This calls NeckoChild::DeallocPRemoteOpenFile(), which deletes |this| if
   // IPDL holds the last reference.  Don't rely on |this| existing after here!
   Send__delete__(this);
 #endif
 
   return true;
 }
 
+void
+RemoteOpenFileChild::AddIPDLReference()
+{
+  AddRef();
+}
+
+void
+RemoteOpenFileChild::ReleaseIPDLReference()
+{
+  // if we haven't gotten fd from parent yet, we're not going to.
+  if (mListener) {
+    mListener->OnRemoteFileOpenComplete(NS_ERROR_UNEXPECTED);
+    mListener = nullptr;
+  }
+
+  Release();
+}
+
 //-----------------------------------------------------------------------------
 // RemoteOpenFileChild::nsIFile functions that we override logic for
 //-----------------------------------------------------------------------------
 
 NS_IMETHODIMP
 RemoteOpenFileChild::Clone(nsIFile **file)
 {
   *file = new RemoteOpenFileChild(*this);
@@ -726,8 +657,9 @@ RemoteOpenFileChild::GetHashCode(uint32_
   if (hashable) {
     return hashable->GetHashCode(aResult);
   }
   return NS_ERROR_UNEXPECTED;
 }
 
 } // namespace net
 } // namespace mozilla
+

--- a/netwerk/ipc/RemoteOpenFileChild.h
+++ b/netwerk/ipc/RemoteOpenFileChild.h
@@ -4,26 +4,20 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #ifndef _RemoteOpenFileChild_h
 #define _RemoteOpenFileChild_h
 
 #include "mozilla/dom/TabChild.h"
 #include "mozilla/net/PRemoteOpenFileChild.h"
-#include "nsICachedFileDescriptorListener.h"
 #include "nsILocalFile.h"
 #include "nsIRemoteOpenFileListener.h"
 
 namespace mozilla {
-
-namespace ipc {
-class FileDescriptor;
-}
-
 namespace net {
 
 /**
  * RemoteOpenFileChild: a thin wrapper around regular nsIFile classes that does
  * IPC to open a file handle on parent instead of child.  Used when we can't
  * open file handle on child (don't have permission), but we don't want the
  * overhead of shipping all I/O traffic across IPDL.  Example: JAR files.
  *
@@ -39,75 +33,55 @@ namespace net {
  *
  * This class should only be instantiated in a child process.
  *
  */
 class RemoteOpenFileChild MOZ_FINAL
   : public PRemoteOpenFileChild
   , public nsIFile
   , public nsIHashable
-  , public nsICachedFileDescriptorListener
 {
-  typedef mozilla::dom::TabChild TabChild;
-  typedef mozilla::ipc::FileDescriptor FileDescriptor;
-
 public:
   RemoteOpenFileChild()
     : mNSPRFileDesc(nullptr)
     , mAsyncOpenCalled(false)
     , mNSPROpenCalled(false)
   {}
 
   virtual ~RemoteOpenFileChild();
 
   NS_DECL_ISUPPORTS
   NS_DECL_NSIFILE
   NS_DECL_NSIHASHABLE
 
   // URI must be scheme 'remoteopenfile://': otherwise looks like a file:// uri.
   nsresult Init(nsIURI* aRemoteOpenUri);
 
+  void AddIPDLReference();
+  void ReleaseIPDLReference();
+
   // Send message to parent to tell it to open file handle for file.
   // TabChild is required, for IPC security.
   // Note: currently only PR_RDONLY is supported for 'flags'
   nsresult AsyncRemoteFileOpen(int32_t aFlags,
                                nsIRemoteOpenFileListener* aListener,
                                nsITabChild* aTabChild);
-
-  void ReleaseIPDLReference()
-  {
-    Release();
-  }
-
 private:
   RemoteOpenFileChild(const RemoteOpenFileChild& other);
 
 protected:
-  void AddIPDLReference()
-  {
-    AddRef();
-  }
-
   virtual bool RecvFileOpened(const FileDescriptor&);
   virtual bool RecvFileDidNotOpen();
 
-  virtual void OnCachedFileDescriptor(const nsAString& aPath,
-                                      const FileDescriptor& aFD) MOZ_OVERRIDE;
-
-  void HandleFileDescriptorAndNotifyListener(const FileDescriptor&,
-                                             bool aFromRecvFileOpened);
-
-  void NotifyListener(nsresult aResult);
-
   // regular nsIFile object, that we forward most calls to.
   nsCOMPtr<nsIFile> mFile;
   nsCOMPtr<nsIURI> mURI;
   nsCOMPtr<nsIRemoteOpenFileListener> mListener;
-  nsRefPtr<TabChild> mTabChild;
   PRFileDesc* mNSPRFileDesc;
   bool mAsyncOpenCalled;
   bool mNSPROpenCalled;
 };
 
 } // namespace net
 } // namespace mozilla
 
 #endif // _RemoteOpenFileChild_h
+