Bug 1130913: Only create a new decoder if we have a new media segment. r=mattwoodrow

dom/media/mediasource/TrackBuffer.cpp

@@ -211,7 +211,7 @@ TrackBuffer::AppendData(LargeDataBuffer* aData, int64_t aTimestampOffset)
   }
 
   if (gotMedia) {
-    if (mLastEndTimestamp &&
+    if (mParser->IsMediaSegmentPresent(aData) && mLastEndTimestamp &&
         (!mParser->TimestampsFuzzyEqual(start, mLastEndTimestamp.value()) ||
          mLastTimestampOffset != aTimestampOffset ||
          mDecoderPerSegment ||
@@ -256,11 +256,12 @@ TrackBuffer::AppendData(LargeDataBuffer* aData, int64_t aTimestampOffset)
     // We're going to have to wait for the decoder to initialize, the promise
     // will be resolved once initialization completes.
     return p;
-  } else if (gotMedia) {
-    // Tell our reader that we have more data to ensure that playback starts if
-    // required when data is appended.
-    mParentDecoder->GetReader()->MaybeNotifyHaveData();
   }
+
+  // Tell our reader that we have more data to ensure that playback starts if
+  // required when data is appended.
+  mParentDecoder->GetReader()->MaybeNotifyHaveData();
+
   mInitializationPromise.Resolve(gotMedia, __func__);
   return p;
 }