bug 1217625 remove unused MessageQueue() and document message queue thread access r=padenot

--HG--
extra : rebase_source : f28aa4521c0d9c7b323a9f280e5c3be367594b18

dom/media/MediaStreamGraphImpl.h

@@ -186,13 +186,6 @@ public:
     return mLifecycleState == LIFECYCLE_RUNNING;
   }
 
-  // Get the message queue, from the current GraphDriver thread.
-  nsTArray<MessageBlock>& MessageQueue()
-  {
-    mMonitor.AssertCurrentThreadOwns();
-    return mFrontMessageQueue;
-  }
-
   /* This is the end of the current iteration, that is, the current time of the
    * graph. */
   GraphTime IterationEnd() const;
@@ -232,6 +225,8 @@ public:
 
   void SwapMessageQueues()
   {
+    MOZ_ASSERT(CurrentDriver()->OnThread());
+    MOZ_ASSERT(mFrontMessageQueue.IsEmpty());
     mMonitor.AssertCurrentThreadOwns();
     mFrontMessageQueue.SwapElements(mBackMessageQueue);
   }
@@ -592,9 +587,15 @@ public:
    * A list of batches of messages to process. Each batch is processed
    * as an atomic unit.
    */
-  /* Message queue processed by the MSG thread during an iteration. */
+  /*
+   * Message queue processed by the MSG thread during an iteration.
+   * Accessed on graph thread only.
+   */
   nsTArray<MessageBlock> mFrontMessageQueue;
-  /* Message queue in which the main thread appends messages. */
+  /*
+   * Message queue in which the main thread appends messages.
+   * Access guarded by mMonitor.
+   */
   nsTArray<MessageBlock> mBackMessageQueue;
 
   /* True if there will messages to process if we swap the message queues. */