Always wait for DataReady() on Windows WaveOut.

media/audio/audio_output_controller.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 MEDIA_AUDIO_AUDIO_OUTPUT_CONTROLLER_H_
 #define MEDIA_AUDIO_AUDIO_OUTPUT_CONTROLLER_H_
 
 #include "base/callback.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
@@ skipping 84 matching lines @@
     virtual void UpdatePendingBytes(uint32 bytes) = 0;
 
     // Attempt to completely fill |dest|, return the actual number of
     // frames that could be read.
     // |source| may optionally be provided for input data.
     virtual int Read(AudioBus* source, AudioBus* dest) = 0;
 
     // Close this synchronous reader.
     virtual void Close() = 0;
 
-    // Poll if data is ready.
-    // Not reliable, as there is no guarantee that renderer is "new-style"
-    // renderer that writes metadata into buffer. After several unsuccessful
-    // attempts caller should assume the data is ready even if that function
-    // returns false.
+    // Check if data is ready.
     virtual bool DataReady() = 0;
   };
 
   // Factory method for creating an AudioOutputController.
   // This also creates and opens an AudioOutputStream on the audio manager
   // thread, and if this is successful, the |event_handler| will receive an
   // OnCreated() call from the same audio manager thread.  |audio_manager| must
   // outlive AudioOutputController.
   static scoped_refptr<AudioOutputController> Create(
       AudioManager* audio_manager, EventHandler* event_handler,
@@ skipping 115 matching lines @@
   // shutdown and force it to wait for the most delayed task.
   // Also, if we're shutting down, we do not want to poll for more data.
   base::WeakPtrFactory<AudioOutputController> weak_this_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioOutputController);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_AUDIO_OUTPUT_CONTROLLER_H_