Do PerformCleanupOnMainThread() when OfflineAudioContext rendering ends

Currently OfflineAudioContext does not do the clean up when rendering
is finished. This CL adds the clean up process when `oncomplete` event
is fired.

with --repeat-each=50 option.

Bug: 856317
Test: webaudio/Analyser/realtimeanalyser-float-data.html passes
Change-Id: Ia0556f666bc49ddb92666beab4171cfcf5c385ba
Reviewed-on: https://chromium-review.googlesource.com/1237384
Commit-Queue: Hongchan Choi <hongchan@chromium.org>
Reviewed-by: Raymond Toy <rtoy@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#594049}

third_party/blink/renderer/modules/webaudio/base_audio_context.h

@@ -353,6 +353,16 @@ class MODULES_EXPORT BaseAudioContext
 
   const String& Uuid() const { return uuid_; }
 
+  // The audio thread relies on the main thread to perform some operations
+  // over the objects that it owns and controls; |ScheduleMainThreadCleanup()|
+  // posts the task to initiate those.
+  void ScheduleMainThreadCleanup();
+
+  // Handles promise resolving, stopping and finishing up of audio source nodes
+  // etc. Actions that should happen, but can happen asynchronously to the
+  // audio thread making rendering progress.
+  void PerformCleanupOnMainThread();
+
  private:
   friend class AudioContextAutoplayTest;
 
@@ -392,18 +402,6 @@ class MODULES_EXPORT BaseAudioContext
   // these Promises.
   void ResolvePromisesForUnpause();
 
-  // The audio thread relies on the main thread to perform some operations
-  // over the objects that it owns and controls; |ScheduleMainThreadCleanup()|
-  // posts the task to initiate those.
-  //
-  // That is, we combine all those sub-tasks into one task action for
-  // convenience and performance, |PerformCleanupOnMainThread()|. It handles
-  // promise resolving, stopping and finishing up of audio source nodes etc.
-  // Actions that should happen, but can happen asynchronously to the
-  // audio thread making rendering progress.
-  void ScheduleMainThreadCleanup();
-  void PerformCleanupOnMainThread();
-
   // When the context is going away, reject any pending script promise
   // resolvers.
   virtual void RejectPendingResolvers();

third_party/blink/renderer/modules/webaudio/offline_audio_context.cc

@@ -379,6 +379,8 @@ void OfflineAudioContext::FireCompletionEvent() {
   }
 
   is_rendering_started_ = false;
+
+  PerformCleanupOnMainThread();
 }
 
 bool OfflineAudioContext::HandlePreOfflineRenderTasks() {