Allow AudioDevice to be constructed on any thread

content/renderer/media/audio_device.cc

 // 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.
 
 #include "content/renderer/media/audio_device.h"
 
 #include "base/debug/trace_event.h"
 #include "base/message_loop.h"
 #include "base/threading/thread_restrictions.h"
 #include "base/time.h"
@@ skipping 28 matching lines @@
   DISALLOW_COPY_AND_ASSIGN(AudioThreadCallback);
 };
 
 AudioDevice::AudioDevice()
     : ScopedLoopObserver(ChildProcess::current()->io_message_loop()),
       callback_(NULL),
       volume_(1.0),
       stream_id_(0),
       play_on_start_(true),
       is_started_(false) {
-  filter_ = RenderThreadImpl::current()->audio_message_filter();
+  filter_ = AudioMessageFilter::current();

[henrika (OOO until Aug 14), 2012/06/20 12:33:52]

By not injecting you make it much more difficult to mock the AudioDevice;
something that we will need given how many clients that are using it.  Try
adding a simple unit test where all you do is to create and destroy and
AudioDevice and you will see what I mean.

[henrika (OOO until Aug 14), 2012/06/20 17:15:53]

Bad example; sorry. I meant create the AD and perform any operation on it which
requires an existing filter.

 }
 
 AudioDevice::AudioDevice(const media::AudioParameters& params,
                          RenderCallback* callback)
     : ScopedLoopObserver(ChildProcess::current()->io_message_loop()),
       audio_parameters_(params),
       callback_(callback),
       volume_(1.0),
       stream_id_(0),
       play_on_start_(true),
       is_started_(false) {
-  filter_ = RenderThreadImpl::current()->audio_message_filter();
+  filter_ = AudioMessageFilter::current();
 }
 
 void AudioDevice::Initialize(const media::AudioParameters& params,
                              RenderCallback* callback) {
   CHECK_EQ(0, stream_id_) <<
       "AudioDevice::Initialize() must be called before Start()";
 
   CHECK(!callback_);  // Calling Initialize() twice?
 
   audio_parameters_ = params;
@@ skipping 220 matching lines @@
   // TODO(crogers/vrk): Figure out a way to avoid the float -> int -> float
   // conversions that happen in the <audio> and WebRTC scenarios.
   media::InterleaveFloatToInt(audio_data_, shared_memory_.memory(),
       audio_parameters_.frames_per_buffer(),
       audio_parameters_.bits_per_sample() / 8);
 
   // Let the host know we are done.
   media::SetActualDataSizeInBytes(&shared_memory_, memory_length_,
       num_frames * audio_parameters_.GetBytesPerFrame());
 }