--- a/widget/gtk/nsWindow.cpp
+++ b/widget/gtk/nsWindow.cpp
@@ -2317,30 +2317,30 @@ nsWindow::OnExposeEvent(cairo_t *cr)
 void
 nsWindow::UpdateAlpha(gfxPattern* aPattern, nsIntRect aBoundsRect)
 {
     // We need to create our own buffer to force the stride to match the
     // expected stride.
     int32_t stride = GetAlignedStride<4>(BytesPerPixel(SurfaceFormat::A8) *
                                          aBoundsRect.width);
     int32_t bufferSize = stride * aBoundsRect.height;
-    nsAutoArrayPtr<uint8_t> imageBuffer(new (std::nothrow) uint8_t[bufferSize]);
+    UniquePtr<uint8_t[]> imageBuffer(new (std::nothrow) uint8_t[bufferSize]);
     RefPtr<DrawTarget> drawTarget = gfxPlatform::GetPlatform()->
-        CreateDrawTargetForData(imageBuffer, aBoundsRect.Size(),
+        CreateDrawTargetForData(imageBuffer.get(), aBoundsRect.Size(),
                                 stride, SurfaceFormat::A8);
 
     if (drawTarget) {
         Matrix transform = Matrix::Translation(-aBoundsRect.x, -aBoundsRect.y);
         drawTarget->SetTransform(transform);
 
         drawTarget->FillRect(Rect(aBoundsRect.x, aBoundsRect.y, aBoundsRect.width, aBoundsRect.height),
                              *aPattern->GetPattern(drawTarget),
                              DrawOptions(1.0, CompositionOp::OP_SOURCE));
     }
-    UpdateTranslucentWindowAlphaInternal(aBoundsRect, imageBuffer, stride);
+    UpdateTranslucentWindowAlphaInternal(aBoundsRect, imageBuffer.get(), stride);
 }
 
 gboolean
 nsWindow::OnConfigureEvent(GtkWidget *aWidget, GdkEventConfigure *aEvent)
 {
     // These events are only received on toplevel windows.
     //
     // GDK ensures that the coordinates are the client window top-left wrt the

--- a/widget/nsBaseWidget.cpp
+++ b/widget/nsBaseWidget.cpp
@@ -687,26 +687,26 @@ nsTransparencyMode nsBaseWidget::GetTran
   return eTransparencyOpaque;
 }
 
 bool
 nsBaseWidget::IsWindowClipRegionEqual(const nsTArray<nsIntRect>& aRects)
 {
   return mClipRects &&
          mClipRectCount == aRects.Length() &&
-         memcmp(mClipRects, aRects.Elements(), sizeof(nsIntRect)*mClipRectCount) == 0;
+         memcmp(mClipRects.get(), aRects.Elements(), sizeof(nsIntRect)*mClipRectCount) == 0;
 }
 
 void
 nsBaseWidget::StoreWindowClipRegion(const nsTArray<nsIntRect>& aRects)
 {
   mClipRectCount = aRects.Length();
-  mClipRects = new nsIntRect[mClipRectCount];
+  mClipRects = MakeUnique<nsIntRect[]>(mClipRectCount);
   if (mClipRects) {
-    memcpy(mClipRects, aRects.Elements(), sizeof(nsIntRect)*mClipRectCount);
+    memcpy(mClipRects.get(), aRects.Elements(), sizeof(nsIntRect)*mClipRectCount);
   }
 }
 
 void
 nsBaseWidget::GetWindowClipRegion(nsTArray<nsIntRect>* aRects)
 {
   if (mClipRects) {
     aRects->AppendElements(mClipRects.get(), mClipRectCount);

--- a/widget/nsBaseWidget.h
+++ b/widget/nsBaseWidget.h
@@ -504,17 +504,17 @@ protected:
   SetAllowedTouchBehaviorCallback mSetAllowedTouchBehaviorCallback;
   RefPtr<WidgetShutdownObserver> mShutdownObserver;
   RefPtr<TextEventDispatcher> mTextEventDispatcher;
   nsCursor          mCursor;
   nsBorderStyle     mBorderStyle;
   nsIntRect         mBounds;
   nsIntRect*        mOriginalBounds;
   // When this pointer is null, the widget is not clipped
-  nsAutoArrayPtr<nsIntRect> mClipRects;
+  mozilla::UniquePtr<nsIntRect[]> mClipRects;
   uint32_t          mClipRectCount;
   nsSizeMode        mSizeMode;
   nsPopupLevel      mPopupLevel;
   nsPopupType       mPopupType;
   SizeConstraints   mSizeConstraints;
 
   bool              mUpdateCursor;
   bool              mUseAttachedEvents;

--- a/widget/nsPrimitiveHelpers.cpp
+++ b/widget/nsPrimitiveHelpers.cpp
@@ -54,21 +54,21 @@ nsPrimitiveHelpers :: CreatePrimitiveFor
       NS_ADDREF(*aPrimitive = primitive);
     }
   }
   else {
     nsCOMPtr<nsISupportsString> primitive =
         do_CreateInstance(NS_SUPPORTS_STRING_CONTRACTID);
     if (primitive ) {
       if (aDataLen % 2) {
-        nsAutoArrayPtr<char> buffer(new char[aDataLen + 1]);
+        auto buffer = MakeUnique<char[]>(aDataLen + 1);
         if (!MOZ_LIKELY(buffer))
           return;
 
-        memcpy(buffer, aDataBuff, aDataLen);
+        memcpy(buffer.get(), aDataBuff, aDataLen);
         buffer[aDataLen] = 0;
         const char16_t* start = reinterpret_cast<const char16_t*>(buffer.get());
         // recall that length takes length as characters, not bytes
         primitive->SetData(Substring(start, start + (aDataLen + 1) / 2));
       } else {
         const char16_t* start = reinterpret_cast<const char16_t*>(aDataBuff);
         // recall that length takes length as characters, not bytes
         primitive->SetData(Substring(start, start + (aDataLen / 2)));

--- a/widget/nsTransferable.cpp
+++ b/widget/nsTransferable.cpp
@@ -178,32 +178,33 @@ DataStruct::ReadCache(nsISupports** aDat
     int64_t fileSize;
     int64_t max32 = 0xFFFFFFFF;
     cacheFile->GetFileSize(&fileSize);
     if (fileSize > max32)
       return NS_ERROR_OUT_OF_MEMORY;
 
     uint32_t size = uint32_t(fileSize);
     // create new memory for the large clipboard data
-    nsAutoArrayPtr<char> data(new char[size]);
+    auto data = MakeUnique<char[]>(size);
     if ( !data )
       return NS_ERROR_OUT_OF_MEMORY;
       
     // now read it all in
     nsCOMPtr<nsIInputStream> inStr;
     NS_NewLocalFileInputStream( getter_AddRefs(inStr),
                                 cacheFile);
     
     if (!cacheFile) return NS_ERROR_FAILURE;
 
-    nsresult rv = inStr->Read(data, fileSize, aDataLen);
+    nsresult rv = inStr->Read(data.get(), fileSize, aDataLen);
 
     // make sure we got all the data ok
     if (NS_SUCCEEDED(rv) && *aDataLen == size) {
-      nsPrimitiveHelpers::CreatePrimitiveForData ( mFlavor.get(), data, fileSize, aData );
+      nsPrimitiveHelpers::CreatePrimitiveForData(mFlavor.get(), data.get(),
+                                                 fileSize, aData);
       return *aData ? NS_OK : NS_ERROR_FAILURE;
     }
 
     // zero the return params
     *aData    = nullptr;
     *aDataLen = 0;
   }
 

--- a/widget/windows/LSPAnnotator.cpp
+++ b/widget/windows/LSPAnnotator.cpp
@@ -61,17 +61,17 @@ LSPAnnotationGatherer::Run()
   // Get the size of the buffer we need
   if (SOCKET_ERROR != WSCEnumProtocols(nullptr, nullptr, &size, &err) ||
       err != WSAENOBUFS) {
     // Er, what?
     NS_NOTREACHED("WSCEnumProtocols suceeded when it should have failed ...");
     return NS_ERROR_FAILURE;
   }
 
-  nsAutoArrayPtr<char> byteArray(new char[size]);
+  auto byteArray = MakeUnique<char[]>(size);
   WSAPROTOCOL_INFOW* providers =
     reinterpret_cast<WSAPROTOCOL_INFOW*>(byteArray.get());
 
   int n = WSCEnumProtocols(nullptr, providers, &size, &err);
   if (n == SOCKET_ERROR) {
     // Lame. We provided the right size buffer; we'll just give up now.
     NS_WARNING("Could not get LSP list");
     return NS_ERROR_FAILURE;

--- a/widget/windows/nsFilePicker.cpp
+++ b/widget/windows/nsFilePicker.cpp
@@ -5,32 +5,35 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "nsFilePicker.h"
 
 #include <shlobj.h>
 #include <shlwapi.h>
 #include <cderr.h>
 
+#include "mozilla/UniquePtr.h"
 #include "mozilla/WindowsVersion.h"
 #include "nsReadableUtils.h"
 #include "nsNetUtil.h"
 #include "nsWindow.h"
 #include "nsILoadContext.h"
 #include "nsIServiceManager.h"
 #include "nsIURL.h"
 #include "nsIStringBundle.h"
 #include "nsEnumeratorUtils.h"
 #include "nsCRT.h"
 #include "nsString.h"
 #include "nsToolkit.h"
 #include "WinUtils.h"
 #include "nsPIDOMWindow.h"
 
 using mozilla::IsVistaOrLater;
+using mozilla::MakeUnique;
+using mozilla::UniquePtr;
 using namespace mozilla::widget;
 
 char16_t *nsFilePicker::mLastUsedUnicodeDirectory;
 char nsFilePicker::mLastUsedDirectory[MAX_PATH+1] = { 0 };
 
 static const wchar_t kDialogPtrProp[] = L"DialogPtrProperty";
 static const DWORD kDialogTimerID = 9999;
 static const unsigned long kDialogTimerTimeout = 300;
@@ -65,33 +68,33 @@ private:
 };
 
 // Manages the current working path.
 class AutoRestoreWorkingPath
 {
 public:
   AutoRestoreWorkingPath() {
     DWORD bufferLength = GetCurrentDirectoryW(0, nullptr);
-    mWorkingPath = new wchar_t[bufferLength];
-    if (GetCurrentDirectoryW(bufferLength, mWorkingPath) == 0) {
+    mWorkingPath = MakeUnique<wchar_t[]>(bufferLength);
+    if (GetCurrentDirectoryW(bufferLength, mWorkingPath.get()) == 0) {
       mWorkingPath = nullptr;
     }
   }
 
   ~AutoRestoreWorkingPath() {
     if (HasWorkingPath()) {
-      ::SetCurrentDirectoryW(mWorkingPath);
+      ::SetCurrentDirectoryW(mWorkingPath.get());
     }
   }
 
   inline bool HasWorkingPath() const {
     return mWorkingPath != nullptr;
   }
 private:
-  nsAutoArrayPtr<wchar_t> mWorkingPath;
+  UniquePtr<wchar_t[]> mWorkingPath;
 };
 
 // Manages NS_NATIVE_TMP_WINDOW child windows. NS_NATIVE_TMP_WINDOWs are
 // temporary child windows of mParentWidget created to address RTL issues
 // in picker dialogs. We are responsible for destroying these.
 class AutoDestroyTmpWindow
 {
 public:
@@ -518,26 +521,26 @@ nsFilePicker::SetDialogHandle(HWND aWnd)
 
 // Open the older XP style folder picker dialog. We end up in this call
 // on XP systems or when platform is built without the longhorn SDK.
 bool
 nsFilePicker::ShowXPFolderPicker(const nsString& aInitialDir)
 {
   bool result = false;
 
-  nsAutoArrayPtr<wchar_t> dirBuffer(new wchar_t[FILE_BUFFER_SIZE]);
-  wcsncpy(dirBuffer, aInitialDir.get(), FILE_BUFFER_SIZE);
+  auto dirBuffer = MakeUnique<wchar_t[]>(FILE_BUFFER_SIZE);
+  wcsncpy(dirBuffer.get(), aInitialDir.get(), FILE_BUFFER_SIZE);
   dirBuffer[FILE_BUFFER_SIZE-1] = '\0';
 
   AutoDestroyTmpWindow adtw((HWND)(mParentWidget.get() ?
     mParentWidget->GetNativeData(NS_NATIVE_TMP_WINDOW) : nullptr));
 
   BROWSEINFOW browserInfo = {0};
   browserInfo.pidlRoot       = nullptr;
-  browserInfo.pszDisplayName = dirBuffer;
+  browserInfo.pszDisplayName = dirBuffer.get();
   browserInfo.lpszTitle      = mTitle.get();
   browserInfo.ulFlags        = BIF_USENEWUI | BIF_RETURNONLYFSDIRS;
   browserInfo.hwndOwner      = adtw.get(); 
   browserInfo.iImage         = 0;
   browserInfo.lParam         = reinterpret_cast<LPARAM>(this);
 
   if (!aInitialDir.IsEmpty()) {
     // the dialog is modal so that |initialDir.get()| will be valid in 
@@ -546,19 +549,19 @@ nsFilePicker::ShowXPFolderPicker(const n
     browserInfo.lpfn   = &BrowseCallbackProc;
   } else {
     browserInfo.lParam = 0;
     browserInfo.lpfn   = nullptr;
   }
 
   LPITEMIDLIST list = ::SHBrowseForFolderW(&browserInfo);
   if (list) {
-    result = ::SHGetPathFromIDListW(list, dirBuffer);
+    result = ::SHGetPathFromIDListW(list, dirBuffer.get());
     if (result)
-      mUnicodeFile.Assign(static_cast<const wchar_t*>(dirBuffer));
+      mUnicodeFile.Assign(static_cast<const wchar_t*>(dirBuffer.get()));
     // free PIDL
     CoTaskMemFree(list);
   }
 
   return result;
 }
 
 /*
@@ -662,31 +665,31 @@ nsFilePicker::FilePickerWrapper(OPENFILE
 
 bool
 nsFilePicker::ShowXPFilePicker(const nsString& aInitialDir)
 {
   OPENFILENAMEW ofn = {0};
   ofn.lStructSize = sizeof(ofn);
   nsString filterBuffer = mFilterList;
                                 
-  nsAutoArrayPtr<wchar_t> fileBuffer(new wchar_t[FILE_BUFFER_SIZE]);
-  wcsncpy(fileBuffer,  mDefaultFilePath.get(), FILE_BUFFER_SIZE);
+  auto fileBuffer = MakeUnique<wchar_t[]>(FILE_BUFFER_SIZE);
+  wcsncpy(fileBuffer.get(),  mDefaultFilePath.get(), FILE_BUFFER_SIZE);
   fileBuffer[FILE_BUFFER_SIZE-1] = '\0'; // null terminate in case copy truncated
 
   if (!aInitialDir.IsEmpty()) {
     ofn.lpstrInitialDir = aInitialDir.get();
   }
 
   AutoDestroyTmpWindow adtw((HWND) (mParentWidget.get() ?
     mParentWidget->GetNativeData(NS_NATIVE_TMP_WINDOW) : nullptr));
 
   ofn.lpstrTitle   = (LPCWSTR)mTitle.get();
   ofn.lpstrFilter  = (LPCWSTR)filterBuffer.get();
   ofn.nFilterIndex = mSelectedType;
-  ofn.lpstrFile    = fileBuffer;
+  ofn.lpstrFile    = fileBuffer.get();
   ofn.nMaxFile     = FILE_BUFFER_SIZE;
   ofn.hwndOwner    = adtw.get();
   ofn.lCustData    = reinterpret_cast<LPARAM>(this);
   ofn.Flags = OFN_SHAREAWARE | OFN_LONGNAMES | OFN_OVERWRITEPROMPT |
               OFN_HIDEREADONLY | OFN_PATHMUSTEXIST | OFN_ENABLESIZING | 
               OFN_EXPLORER;
 
   // Windows Vista and up won't allow you to use the new looking dialogs with
@@ -749,19 +752,19 @@ nsFilePicker::ShowXPFilePicker(const nsS
       // allocated and that the returned value should be freed by the caller.
       // If the hook changes the buffer, it will deallocate the old buffer.
       // This fix would be nice to have in Vista and up, but it would force
       // the file picker to use the old style dialogs because hooks are not
       // allowed in the new file picker UI.  We need to eventually move to
       // the new Common File Dialogs for Vista and up.
       if (!IsVistaOrLater()) {
         ofn.lpfnHook = MultiFilePickerHook;
-        fileBuffer.forget();
+        fileBuffer.release();
         result = FilePickerWrapper(&ofn, PICKER_TYPE_OPEN);
-        fileBuffer = ofn.lpstrFile;
+        fileBuffer.reset(ofn.lpstrFile);
       } else {
         result = FilePickerWrapper(&ofn, PICKER_TYPE_OPEN);
       }
       break;
 
     case modeSave:
       {
         ofn.Flags |= OFN_NOREADONLYRETURN;
@@ -793,27 +796,27 @@ nsFilePicker::ShowXPFilePicker(const nsS
   if (!result)
     return false;
 
   // Remember what filter type the user selected
   mSelectedType = (int16_t)ofn.nFilterIndex;
 
   // Single file selection, we're done
   if (mMode != modeOpenMultiple) {
-    GetQualifiedPath(fileBuffer, mUnicodeFile);
+    GetQualifiedPath(fileBuffer.get(), mUnicodeFile);
     return true;
   }
 
   // Set user-selected location of file or directory.  From msdn's "Open and
   // Save As Dialog Boxes" section:
   // If you specify OFN_EXPLORER, the directory and file name strings are '\0'
   // separated, with an extra '\0' character after the last file name. This
   // format enables the Explorer-style dialog boxes to return long file names
   // that include spaces. 
-  wchar_t *current = fileBuffer;
+  wchar_t *current = fileBuffer.get();
   
   nsAutoString dirName(current);
   // Sometimes dirName contains a trailing slash and sometimes it doesn't:
   if (current[dirName.Length() - 1] != '\\')
     dirName.Append((char16_t)'\\');
   
   while (current && *current && *(current + wcslen(current) + 1)) {
     current = current + wcslen(current) + 1;
@@ -834,17 +837,17 @@ nsFilePicker::ShowXPFilePicker(const nsS
     if (NS_FAILED(file->InitWithPath(canonicalizedPath)) ||
         !mFiles.AppendObject(file))
       return false;
   }
   
   // Handle the case where the user selected just one file. From msdn: If you
   // specify OFN_ALLOWMULTISELECT and the user selects only one file the
   // lpstrFile string does not have a separator between the path and file name.
-  if (current && *current && (current == fileBuffer)) {
+  if (current && *current && (current == fileBuffer.get())) {
     nsCOMPtr<nsIFile> file = do_CreateInstance("@mozilla.org/file/local;1");
     NS_ENSURE_TRUE(file, false);
     
     nsAutoString canonicalizedPath;
     GetQualifiedPath(current, canonicalizedPath);
     if (NS_FAILED(file->InitWithPath(canonicalizedPath)) ||
         !mFiles.AppendObject(file))
       return false;