Bug 1285987: Narrow the workaround added in bug 1276184 to only be effective with webm. r=gerald

Some invalid streams incorrectly tag all frames as keyframes, which cause the frames to be inserted in the wrong order in the trackbuffer.

MozReview-Commit-ID: EZurdiMxmle

--HG--
extra : rebase_source : d739eecb9e5b06aaeefcf044b5735949db86522d

dom/media/mediasource/TrackBuffersManager.cpp

@@ -1625,10 +1625,17 @@ TrackBuffersManager::InsertFrames(TrackBuffer& aSamples,
   intersection.Intersection(aIntervals);
 
   if (intersection.Length()) {
-    if (aSamples[0]->mKeyframe) {
+    if (aSamples[0]->mKeyframe &&
+        (mType.LowerCaseEqualsLiteral("video/webm") ||
+         mType.LowerCaseEqualsLiteral("audio/webm"))) {
       // We are starting a new GOP, we do not have to worry about breaking an
       // existing current coded frame group. Reset the next insertion index
       // so the search for when to start our frames removal can be exhaustive.
+      // This is a workaround for bug 1276184 and only until either bug 1277733
+      // or bug 1209386 is fixed.
+      // With the webm container, we can't always properly determine the
+      // duration of the last frame, which may cause the last frame of a cluster
+      // to overlap the following frame.
       trackBuffer.mNextInsertionIndex.reset();
     }
     size_t index =