Bug 1401461. P1 - remove ChannelMediaResource::Listener::Revoke(). r=gerald

See comment 0 for the rationale. We check |aRequest != mResource->mChannel|
to know if a new channel is being loaded and the call should be aborted.

MozReview-Commit-ID: 6G1x7cXNvAq

--HG--
extra : rebase_source : 3114979192346e257f5d8040b8e0ffffa419d3f5
extra : source : eeb067bc2905dfa6fb5764fd42ebb78e1b71a61d

dom/media/ChannelMediaResource.cpp

@@ -68,8 +68,9 @@ nsresult
 ChannelMediaResource::Listener::OnStartRequest(nsIRequest* aRequest,
                                                nsISupports* aContext)
 {
-  if (!mResource)
+  if (aRequest != mResource->mChannel) {
     return NS_OK;
+  }
   return mResource->OnStartRequest(aRequest, mOffset);
 }
 
@@ -78,8 +79,9 @@ ChannelMediaResource::Listener::OnStopRequest(nsIRequest* aRequest,
                                               nsISupports* aContext,
                                               nsresult aStatus)
 {
-  if (!mResource)
+  if (aRequest != mResource->mChannel) {
     return NS_OK;
+  }
   return mResource->OnStopRequest(aRequest, aStatus);
 }
 
@@ -91,7 +93,9 @@ ChannelMediaResource::Listener::OnDataAvailable(nsIRequest* aRequest,
                                                 uint32_t aCount)
 {
   // This might happen off the main thread.
-  MOZ_DIAGNOSTIC_ASSERT(mResource);
+  // Don't check |aRequest != mResource->mChannel| for it is a data race to read
+  // mResource->mChannel off the main thread. Instead we check the load ID to
+  // determine if the data is from an old channel.
   return mResource->OnDataAvailable(mLoadID, aStream, aCount);
 }
 
@@ -103,7 +107,7 @@ ChannelMediaResource::Listener::AsyncOnChannelRedirect(
   nsIAsyncVerifyRedirectCallback* cb)
 {
   nsresult rv = NS_OK;
-  if (mResource) {
+  if (aOld == mResource->mChannel) {
     rv = mResource->OnChannelRedirect(aOld, aNew, aFlags, mOffset);
   }
 
@@ -415,8 +419,6 @@ ChannelMediaResource::OnDataAvailable(uint32_t aLoadID,
                                       uint32_t aCount)
 {
   // This might happen off the main thread.
-  // Don't assert |mChannel.get() == aRequest| since reading mChannel here off
-  // the main thread is a data race.
 
   RefPtr<ChannelMediaResource> self = this;
   nsCOMPtr<nsIRunnable> r = NS_NewRunnableFunction(
@@ -587,7 +589,6 @@ void ChannelMediaResource::CloseChannel()
   }
 
   if (mListener) {
-    mListener->Revoke();
     mListener = nullptr;
   }
 }

dom/media/ChannelMediaResource.h

@@ -128,10 +128,8 @@ public:
     NS_DECL_NSIINTERFACEREQUESTOR
     NS_DECL_NSITHREADRETARGETABLESTREAMLISTENER
 
-    void Revoke() { mResource = nullptr; }
-
   private:
-    RefPtr<ChannelMediaResource> mResource;
+    const RefPtr<ChannelMediaResource> mResource;
     const int64_t mOffset;
     const uint32_t mLoadID;
   };