--- a/browser/devtools/webconsole/test/browser.ini
+++ b/browser/devtools/webconsole/test/browser.ini
@@ -302,17 +302,16 @@ skip-if = buildapp == 'mulet' || e10s # 
 [browser_webconsole_bug_915141_toggle_response_logging_with_keyboard.js]
 [browser_webconsole_filter_buttons_contextmenu.js]
 [browser_webconsole_bug_1006027_message_timestamps_incorrect.js]
 skip-if = e10s # Bug 1042253 - webconsole e10s tests (Linux debug intermittent)
 [browser_webconsole_bug_1010953_cspro.js]
 [browser_webconsole_certificate_messages.js]
 skip-if = e10s # Bug 1042253 - webconsole tests disabled with e10s
 [browser_webconsole_show_subresource_security_errors.js]
-skip-if = e10s # Bug 1042253 - webconsole tests disabled with e10s
 [browser_webconsole_cached_autocomplete.js]
 [browser_webconsole_change_font_size.js]
 [browser_webconsole_chrome.js]
 [browser_webconsole_clickable_urls.js]
 skip-if = e10s # Bug 1042253 - webconsole e10s tests (Linux debug timeout)
 [browser_webconsole_closure_inspection.js]
 skip-if = e10s # Bug 1042253 - webconsole tests disabled with e10s
 [browser_webconsole_completion.js]

--- a/netwerk/protocol/http/HttpBaseChannel.h
+++ b/netwerk/protocol/http/HttpBaseChannel.h
@@ -177,17 +177,17 @@ public:
   NS_IMETHOD GetLocalPort(int32_t* port) override;
   NS_IMETHOD GetRemoteAddress(nsACString& addr) override;
   NS_IMETHOD GetRemotePort(int32_t* port) override;
   NS_IMETHOD GetAllowSpdy(bool *aAllowSpdy) override;
   NS_IMETHOD SetAllowSpdy(bool aAllowSpdy) override;
   NS_IMETHOD GetAllowAltSvc(bool *aAllowAltSvc) override;
   NS_IMETHOD SetAllowAltSvc(bool aAllowAltSvc) override;
   NS_IMETHOD GetApiRedirectToURI(nsIURI * *aApiRedirectToURI) override;
-  nsresult AddSecurityMessage(const nsAString &aMessageTag, const nsAString &aMessageCategory);
+  virtual nsresult AddSecurityMessage(const nsAString &aMessageTag, const nsAString &aMessageCategory);
   NS_IMETHOD TakeAllSecurityMessages(nsCOMArray<nsISecurityConsoleMessage> &aMessages) override;
   NS_IMETHOD GetResponseTimeoutEnabled(bool *aEnable) override;
   NS_IMETHOD SetResponseTimeoutEnabled(bool aEnable) override;
   NS_IMETHOD GetNetworkInterfaceId(nsACString& aNetworkInterfaceId) override;
   NS_IMETHOD SetNetworkInterfaceId(const nsACString& aNetworkInterfaceId) override;
   NS_IMETHOD AddRedirect(nsIPrincipal *aRedirect) override;
   NS_IMETHOD ForcePending(bool aForcePending) override;
   NS_IMETHOD GetLastModifiedTime(PRTime* lastModifiedTime) override;

--- a/netwerk/protocol/http/HttpChannelChild.cpp
+++ b/netwerk/protocol/http/HttpChannelChild.cpp
@@ -986,16 +986,24 @@ HttpChannelChild::RecvDeleteSelf()
 }
 
 void
 HttpChannelChild::DeleteSelf()
 {
   Send__delete__(this);
 }
 
+bool
+HttpChannelChild::RecvReportSecurityMessage(const nsString& messageTag,
+                                            const nsString& messageCategory)
+{
+  AddSecurityMessage(messageTag, messageCategory);
+  return true;
+}
+
 class Redirect1Event : public ChannelEvent
 {
  public:
   Redirect1Event(HttpChannelChild* child,
                  const uint32_t& newChannelId,
                  const URIParams& newURI,
                  const uint32_t& redirectFlags,
                  const nsHttpResponseHead& responseHead)

--- a/netwerk/protocol/http/HttpChannelChild.h
+++ b/netwerk/protocol/http/HttpChannelChild.h
@@ -135,16 +135,19 @@ protected:
                           const nsHttpResponseHead& responseHead) override;
   bool RecvRedirect3Complete() override;
   bool RecvAssociateApplicationCache(const nsCString& groupID,
                                      const nsCString& clientID) override;
   bool RecvFlushedForDiversion() override;
   bool RecvDivertMessages() override;
   bool RecvDeleteSelf() override;
 
+  bool RecvReportSecurityMessage(const nsString& messageTag,
+                                 const nsString& messageCategory) override;
+
   bool GetAssociatedContentSecurity(nsIAssociatedContentSecurity** res = nullptr);
   virtual void DoNotifyListenerCleanup() override;
 
 private:
   nsresult ContinueAsyncOpen();
 
   void DoOnStartRequest(nsIRequest* aRequest, nsISupports* aContext);
   void DoOnStatus(nsIRequest* aRequest, nsresult status);

--- a/netwerk/protocol/http/HttpChannelParent.cpp
+++ b/netwerk/protocol/http/HttpChannelParent.cpp
@@ -324,16 +324,17 @@ HttpChannelParent::DoAsyncOpen(  const U
   nsCOMPtr<nsIChannel> channel;
   rv = NS_NewChannelInternal(getter_AddRefs(channel), uri, loadInfo,
                              nullptr, nullptr, loadFlags, ios);
 
   if (NS_FAILED(rv))
     return SendFailedAsyncOpen(rv);
 
   mChannel = static_cast<nsHttpChannel *>(channel.get());
+  mChannel->SetWarningReporter(this);
   mChannel->SetTimingEnabled(true);
   if (mPBOverride != kPBOverride_Unset) {
     mChannel->SetPrivate(mPBOverride == kPBOverride_Private ? true : false);
   }
 
   if (doResumeAt)
     mChannel->ResumeAt(startPos, entityID);
 
@@ -1259,9 +1260,24 @@ HttpChannelParent::GetAuthPrompt(uint32_
                                  void** aResult)
 {
   nsCOMPtr<nsIAuthPrompt2> prompt =
     new NeckoParent::NestedFrameAuthPrompt(Manager(), mNestedFrameId);
   prompt.forget(aResult);
   return NS_OK;
 }
 
+//-----------------------------------------------------------------------------
+// HttpChannelSecurityWarningReporter
+//-----------------------------------------------------------------------------
+
+nsresult
+HttpChannelParent::ReportSecurityMessage(const nsAString& aMessageTag,
+                                         const nsAString& aMessageCategory)
+{
+  if (NS_WARN_IF(!SendReportSecurityMessage(nsString(aMessageTag),
+                                            nsString(aMessageCategory)))) {
+    return NS_ERROR_UNEXPECTED;
+  }
+  return NS_OK;
+}
+
 }} // mozilla::net

--- a/netwerk/protocol/http/HttpChannelParent.h
+++ b/netwerk/protocol/http/HttpChannelParent.h
@@ -39,16 +39,17 @@ class HttpChannelParentListener;
 class HttpChannelParent final : public PHttpChannelParent
                               , public nsIParentRedirectingChannel
                               , public nsIProgressEventSink
                               , public nsIInterfaceRequestor
                               , public ADivertableParentChannel
                               , public nsIAuthPromptProvider
                               , public nsINetworkInterceptController
                               , public DisconnectableParent
+                              , public HttpChannelSecurityWarningReporter
 {
   virtual ~HttpChannelParent();
 
 public:
   NS_DECL_ISUPPORTS
   NS_DECL_NSIREQUESTOBSERVER
   NS_DECL_NSISTREAMLISTENER
   NS_DECL_NSIPARENTCHANNEL
@@ -149,16 +150,19 @@ protected:
   void FailDiversion(nsresult aErrorCode, bool aSkipResume = true);
 
   friend class HttpChannelParentListener;
   nsRefPtr<mozilla::dom::TabParent> mTabParent;
 
   void OfflineDisconnect() override;
   uint32_t GetAppId() override;
 
+  nsresult ReportSecurityMessage(const nsAString& aMessageTag,
+                                 const nsAString& aMessageCategory) override;
+
 private:
   nsRefPtr<nsHttpChannel>       mChannel;
   nsCOMPtr<nsICacheEntry>       mCacheEntry;
   nsCOMPtr<nsIAssociatedContentSecurity>  mAssociatedContentSecurity;
   bool mIPCClosed;                // PHttpChannel actor has been Closed()
 
   nsCOMPtr<nsIChannel> mRedirectChannel;
   nsCOMPtr<nsIAsyncVerifyRedirectCallback> mRedirectCallback;

--- a/netwerk/protocol/http/PHttpChannel.ipdl
+++ b/netwerk/protocol/http/PHttpChannel.ipdl
@@ -134,16 +134,20 @@ child:
 
   // Parent has been suspended for diversion; no more events to be enqueued.
   FlushedForDiversion();
 
   // Child should resume processing the ChannelEventQueue, i.e. diverting any
   // OnDataAvailable and OnStopRequest messages in the queue back to the parent.
   DivertMessages();
 
+  // Report a security message to the console associated with this
+  // channel.
+  ReportSecurityMessage(nsString messageTag, nsString messageCategory);
+
   // Tell child to delete channel (all IPDL deletes must be done from child to
   // avoid races: see bug 591708).
   DeleteSelf();
 };
 
 
 } // namespace net
 } // namespace mozilla

--- a/netwerk/protocol/http/nsHttpChannel.cpp
+++ b/netwerk/protocol/http/nsHttpChannel.cpp
@@ -239,16 +239,17 @@ nsHttpChannel::nsHttpChannel()
     , mCacheEntryIsWriteOnly(false)
     , mCacheEntriesToWaitFor(0)
     , mHasQueryString(0)
     , mConcurentCacheAccess(0)
     , mIsPartialRequest(0)
     , mHasAutoRedirectVetoNotifier(0)
     , mPushedStream(nullptr)
     , mLocalBlocklist(false)
+    , mWarningReporter(nullptr)
     , mDidReval(false)
 {
     LOG(("Creating nsHttpChannel [this=%p]\n", this));
     mChannelCreationTime = PR_Now();
     mChannelCreationTimestamp = TimeStamp::Now();
 }
 
 nsHttpChannel::~nsHttpChannel()
@@ -276,16 +277,29 @@ nsHttpChannel::Init(nsIURI *uri,
                                         proxyResolveFlags, proxyURI);
     if (NS_FAILED(rv))
         return rv;
 
     LOG(("nsHttpChannel::Init [this=%p]\n", this));
 
     return rv;
 }
+
+nsresult
+nsHttpChannel::AddSecurityMessage(const nsAString& aMessageTag,
+                                  const nsAString& aMessageCategory)
+{
+    if (mWarningReporter) {
+        return mWarningReporter->ReportSecurityMessage(aMessageTag,
+                                                       aMessageCategory);
+    }
+    return HttpBaseChannel::AddSecurityMessage(aMessageTag,
+                                               aMessageCategory);
+}
+
 //-----------------------------------------------------------------------------
 // nsHttpChannel <private>
 //-----------------------------------------------------------------------------
 
 nsresult
 nsHttpChannel::Connect()
 {
     nsresult rv;

--- a/netwerk/protocol/http/nsHttpChannel.h
+++ b/netwerk/protocol/http/nsHttpChannel.h
@@ -28,16 +28,24 @@ class nsDNSPrefetch;
 class nsICancelable;
 class nsIHttpChannelAuthProvider;
 class nsInputStreamPump;
 class nsISSLStatus;
 
 namespace mozilla { namespace net {
 
 class Http2PushedStream;
+
+class HttpChannelSecurityWarningReporter
+{
+public:
+  virtual nsresult ReportSecurityMessage(const nsAString& aMessageTag,
+                                         const nsAString& aMessageCategory) = 0;
+};
+
 //-----------------------------------------------------------------------------
 // nsHttpChannel
 //-----------------------------------------------------------------------------
 
 // Use to support QI nsIChannel to nsHttpChannel
 #define NS_HTTPCHANNEL_IID                         \
 {                                                  \
   0x301bf95b,                                      \
@@ -136,16 +144,22 @@ public:
     NS_IMETHOD GetDomainLookupStart(mozilla::TimeStamp *aDomainLookupStart) override;
     NS_IMETHOD GetDomainLookupEnd(mozilla::TimeStamp *aDomainLookupEnd) override;
     NS_IMETHOD GetConnectStart(mozilla::TimeStamp *aConnectStart) override;
     NS_IMETHOD GetConnectEnd(mozilla::TimeStamp *aConnectEnd) override;
     NS_IMETHOD GetRequestStart(mozilla::TimeStamp *aRequestStart) override;
     NS_IMETHOD GetResponseStart(mozilla::TimeStamp *aResponseStart) override;
     NS_IMETHOD GetResponseEnd(mozilla::TimeStamp *aResponseEnd) override;
 
+    nsresult AddSecurityMessage(const nsAString& aMessageTag,
+                                const nsAString& aMessageCategory) override;
+
+    void SetWarningReporter(HttpChannelSecurityWarningReporter* aReporter)
+      { mWarningReporter = aReporter; }
+
 public: /* internal necko use only */
 
     void InternalSetUploadStream(nsIInputStream *uploadStream)
       { mUploadStream = uploadStream; }
     void SetUploadStreamHasHeaders(bool hasHeaders)
       { mUploadStreamHasHeaders = hasHeaders; }
 
     nsresult SetReferrerWithPolicyInternal(nsIURI *referrer,
@@ -472,16 +486,19 @@ private:
     bool                              mLocalBlocklist;
 
     nsresult WaitForRedirectCallback();
     void PushRedirectAsyncFunc(nsContinueRedirectionFunc func);
     void PopRedirectAsyncFunc(nsContinueRedirectionFunc func);
 
     nsCString mUsername;
 
+    // If non-null, warnings should be reported to this object.
+    HttpChannelSecurityWarningReporter* mWarningReporter;
+
 protected:
     virtual void DoNotifyListenerCleanup() override;
 
 private: // cache telemetry
     bool mDidReval;
 };
 
 NS_DEFINE_STATIC_IID_ACCESSOR(nsHttpChannel, NS_HTTPCHANNEL_IID)