Add test to make sure if PPB_Audio_Shared::StartThread() works.

ppapi/shared_impl/ppb_audio_shared.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef PPAPI_SHARED_IMPL_PPB_AUDIO_SHARED_H_
 #define PPAPI_SHARED_IMPL_PPB_AUDIO_SHARED_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/shared_memory.h"
 #include "base/sync_socket.h"
@@ skipping 49 matching lines @@
   void SetCallback(const AudioCallbackCombined& callback, void* user_data);
 
   // Configures the current state to be playing or not. The caller is
   // responsible for ensuring the new state is the opposite of the current one.
   //
   // This is the implementation for PPB_Audio.Start/StopPlayback, except that
   // it does not actually notify the audio system to stop playback, it just
   // configures our object to stop generating callbacks. The actual stop
   // playback request will be done in the derived classes and will be different
   // from the proxy and the renderer.
-  void SetStartPlaybackState();
+  bool SetStartPlaybackState();
   void SetStopPlaybackState();
 
   // Sets the shared memory and socket handles. This will automatically start
   // playback if we're currently set to play.
   void SetStreamInfo(PP_Instance instance,
                      base::SharedMemoryHandle shared_memory_handle,
                      size_t shared_memory_size,
                      base::SyncSocket::Handle socket_handle,
                      PP_AudioSampleRate sample_rate,
                      int sample_frame_count);
 
 #if defined(OS_NACL)
   // NaCl has a special API for IRT code to create threads that can call back
   // into user code.
   static void SetThreadFunctions(const struct PP_ThreadFunctions* functions);
 #endif
 
  private:
   // Starts execution of the audio thread.
-  void StartThread();
+  bool StartThread();
 
   // Stop execution of the audio thread.
   void StopThread();
 
   // DelegateSimpleThread::Delegate implementation. Run on the audio thread.
   virtual void Run();
 
   // True if playing the stream.
   bool playing_;
 
@@ skipping 37 matching lines @@
 
   // Buffer index used to coordinate with the browser side audio receiver.
   uint32_t buffer_index_;
 
   DISALLOW_COPY_AND_ASSIGN(PPB_Audio_Shared);
 };
 
 }  // namespace ppapi
 
 #endif  // PPAPI_SHARED_IMPL_PPB_AUDIO_SHARED_H_