Bug 1503132 remove unnecessary monitor notify for AudioCallbackDriver r=padenot

Differential Revision: https://phabricator.services.mozilla.com/D10161

--HG--
extra : moz-landing-system : lando

dom/media/GraphDriver.cpp

@@ -850,13 +850,12 @@ AudioCallbackDriver::AddMixerCallback()
 void
 AudioCallbackDriver::WaitForNextIteration()
 {
+  // Do not block.
 }
 
 void
 AudioCallbackDriver::WakeUp()
 {
-  mGraphImpl->GetMonitor().AssertCurrentThreadOwns();
-  mGraphImpl->GetMonitor().Notify();
 }
 
 void

dom/media/GraphDriver.h

@@ -116,8 +116,8 @@ public:
   explicit GraphDriver(MediaStreamGraphImpl* aGraphImpl);
 
   NS_INLINE_DECL_THREADSAFE_REFCOUNTING(GraphDriver);
-  /* For real-time graphs, this waits until it's time to process more data. For
-   * offline graphs, this is a no-op. */
+  /* For SystemClockDriver, this waits until it's time to process more data.
+   * For other drivers, this is a no-op. */
   virtual void WaitForNextIteration() = 0;
   /* Wakes up the graph if it is waiting. */
   virtual void WakeUp() = 0;