Remove GetAudioManager and GetMediaStreamManager from ResourceContext. The reason is the content mo…

media/audio/audio_manager.h

Index: media/audio/audio_manager.h
===================================================================
--- media/audio/audio_manager.h	(revision 122828)
+++ media/audio/audio_manager.h	(working copy)
@@ -31,6 +31,9 @@
   // NOTE: There should only be one instance.
   static AudioManager* Create();
 
+  // Returns the AudioManager object if it's been created, NULL otherwise.
+  static AudioManager* Get();
+
   // Returns true if the OS reports existence of audio devices. This does not
   // guarantee that the existing devices support all formats and sample rates.
   virtual bool HasAudioOutputDevices() = 0;