Don't switch to fake audio output until stream open fails.

media/audio/audio_output_resampler.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 "media/audio/audio_output_resampler.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/command_line.h"
 #include "base/compiler_specific.h"
@@ skipping 170 matching lines @@
     if (!streams_opened_ &&
         output_params_.format() == AudioParameters::AUDIO_PCM_LOW_LATENCY) {
       UMA_HISTOGRAM_BOOLEAN("Media.FallbackToHighLatencyAudioPath", false);
     }
     streams_opened_ = true;
     return true;
   }
 
   // If we've already tried to open the stream in high latency mode or we've
   // successfully opened a stream previously, there's nothing more to be done.
-  if (output_params_.format() == AudioParameters::AUDIO_PCM_LINEAR ||
+  if (output_params_.format() != AudioParameters::AUDIO_PCM_LOW_LATENCY ||
       streams_opened_ || !callbacks_.empty()) {
     return false;
   }
 
   DCHECK_EQ(output_params_.format(), AudioParameters::AUDIO_PCM_LOW_LATENCY);
 
   if (CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kDisableAudioFallback)) {
     LOG(ERROR) << "Open failed and automatic fallback to high latency audio "
                << "path is disabled, aborting.";
     return false;
   }
 
   DLOG(ERROR) << "Unable to open audio device in low latency mode.  Falling "
               << "back to high latency audio output.";
 
   // Record UMA statistics about the hardware which triggered the failure so
   // we can debug and triage later.
   RecordFallbackStats(output_params_);
   output_params_ = SetupFallbackParams(params_, output_params_);
   Initialize();
+  if (dispatcher_->OpenStream()) {
+    streams_opened_ = true;
+    return true;
+  }
 
-  // Retry, if this fails, there's nothing left to do but report the error back.
-  return dispatcher_->OpenStream();
+  DLOG(ERROR) << "Unable to open audio device in high latency mode.  Falling "
+              << "back to fake audio output.";
+
+  // Finally fall back to a fake audio output device.
+  output_params_.Reset(
+      AudioParameters::AUDIO_FAKE, params_.channel_layout(),
+      params_.input_channels(), params_.sample_rate(),
+      params_.bits_per_sample(), params_.frames_per_buffer());
+  Initialize();
+  if (dispatcher_->OpenStream()) {
+    streams_opened_ = true;
+    return true;
+  }
+
+  return false;
 }
 
 bool AudioOutputResampler::StartStream(
     AudioOutputStream::AudioSourceCallback* callback,
     AudioOutputProxy* stream_proxy) {
   DCHECK_EQ(MessageLoop::current(), message_loop_);
 
   OnMoreDataConverter* resampler_callback = NULL;
   CallbackMap::iterator it = callbacks_.find(stream_proxy);
   if (it == callbacks_.end()) {
@@ skipping 139 matching lines @@
     source_callback_->OnError(stream, code);
 }
 
 void OnMoreDataConverter::WaitTillDataReady() {
   base::AutoLock auto_lock(source_lock_);
   if (source_callback_)
     source_callback_->WaitTillDataReady();
 }
 
 }  // namespace media