Fix media/base 64-bit compilation issues

media/base/audio_bus.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_BASE_AUDIO_BUS_H_
 #define MEDIA_BASE_AUDIO_BUS_H_
 
 #include <vector>
 
 #include "base/memory/aligned_memory.h"
@@ skipping 65 matching lines @@
   // AudioBus object must have the same frames() and channels().
   void CopyTo(AudioBus* dest) const;
 
   // Returns a raw pointer to the requested channel.  Pointer is guaranteed to
   // have a 16-byte alignment.  Warning: Do not rely on having sane (i.e. not
   // inf, nan, or between [-1.0, 1.0]) values in the channel data.
   float* channel(int channel) { return channel_data_[channel]; }
   const float* channel(int channel) const { return channel_data_[channel]; }
   void SetChannelData(int channel, float* data);
 
-  int channels() const { return channel_data_.size(); }
+  int channels() const { return static_cast<int>(channel_data_.size()); }
   int frames() const { return frames_; }
   void set_frames(int frames);
 
   // Helper method for zeroing out all channels of audio data.
   void Zero();
   void ZeroFrames(int frames);
   void ZeroFramesPartial(int start_frame, int frames);
 
  private:
   friend struct base::DefaultDeleter<AudioBus>;
@@ skipping 16 matching lines @@
 
   // Protect SetChannelData() and set_frames() for use by CreateWrapper().
   bool can_set_channel_data_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioBus);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_AUDIO_BUS_H_