Bug 1286810: [MSE] P1. Error on abort() during Range Removals. r=gerald

As per https://github.com/w3c/media-source/issues/26

MozReview-Commit-ID: 1rNKVTBDjFY

dom/media/mediasource/SourceBuffer.cpp

@@ -192,6 +192,10 @@ SourceBuffer::Abort(ErrorResult& aRv)
     aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
     return;
   }
+  if (mPendingRemoval.Exists()) {
+    aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
+    return;
+  }
   AbortBufferAppend();
   ResetParserState();
   mCurrentAttributes.SetAppendWindowStart(0);
@@ -248,11 +252,15 @@ SourceBuffer::RangeRemoval(double aStart, double aEnd)
   StartUpdating();
 
   RefPtr<SourceBuffer> self = this;
+  mPendingRemoval.Begin(
     mTrackBuffersManager->RangeRemoval(TimeUnit::FromSeconds(aStart),
                                        TimeUnit::FromSeconds(aEnd))
       ->Then(AbstractThread::MainThread(), __func__,
-           [self] (bool) { self->StopUpdating(); },
-           []() { MOZ_ASSERT(false); });
+             [self] (bool) {
+               self->mPendingRemoval.Complete();
+               self->StopUpdating();
+             },
+             []() { MOZ_ASSERT(false); }));
 }
 
 void

dom/media/mediasource/SourceBuffer.h

@@ -174,6 +174,7 @@ private:
   mozilla::Atomic<bool> mActive;
 
   MozPromiseRequestHolder<SourceBufferTask::AppendPromise> mPendingAppend;
+  MozPromiseRequestHolder<SourceBufferTask::RangeRemovalPromise> mPendingRemoval;
   const nsCString mType;
 
   RefPtr<TimeRanges> mBuffered;