Fixed the audio backgrounding bug

content/browser/renderer_host/render_process_host_impl.h

Index: content/browser/renderer_host/render_process_host_impl.h
diff --git a/content/browser/renderer_host/render_process_host_impl.h b/content/browser/renderer_host/render_process_host_impl.h
index 8937fd1e561d188c12005ef4fa3f2161b7cfcb6d..a82895ce7e1b509cde2aa2c6c9f22dbc54e8ced1 100644
--- a/content/browser/renderer_host/render_process_host_impl.h
+++ b/content/browser/renderer_host/render_process_host_impl.h
@@ -112,6 +112,8 @@ class CONTENT_EXPORT RenderProcessHostImpl
   void WidgetRestored() override;
   void WidgetHidden() override;
   int VisibleWidgetCount() const override;
+  void AudioStopped() override;
+  void AudioStarted() override;
   bool IsForGuestsOnly() const override;
   StoragePartition* GetStoragePartition() const override;
   bool Shutdown(int exit_code, bool wait) override;
@@ -330,6 +332,7 @@ class CONTENT_EXPORT RenderProcessHostImpl
       base::CommandLine* renderer_cmd) const;
 
   // Callers can reduce the RenderProcess' priority.
+  // Must be called from the IO thread.

[ncarter (slow), 2015/07/06 21:53:57]

I think you mean UI thread (since that's what the DCHECK says).

In any case, RenderProcessHost is single-threaded and only exists on the UI
thread.

[sebsg, 2015/08/02 16:44:23]

Done.

   void SetBackgrounded(bool backgrounded);
 
   // Handle termination of our process.