Fix a couple bugs with OSX audio buffer size selection.

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 106 matching lines @@
     UMA_HISTOGRAM_ENUMERATION(
         "Media.FallbackHardwareAudioSamplesPerSecond",
         asr, kUnexpectedAudioSampleRate);
   } else {
     UMA_HISTOGRAM_COUNTS(
         "Media.FallbackHardwareAudioSamplesPerSecondUnexpected",
         output_params.sample_rate());
   }
 }
 
+// Only Windows has a high latency output driver that is not the same as the low
+// latency path.
+#if defined(OS_WIN)
 // Converts low latency based |output_params| into high latency appropriate
 // output parameters in error situations.
 static AudioParameters SetupFallbackParams(
     const AudioParameters& input_params, const AudioParameters& output_params) {
   // Choose AudioParameters appropriate for opening the device in high latency
   // mode.  |kMinLowLatencyFrameSize| is arbitrarily based on Pepper Flash's
   // MAXIMUM frame size for low latency.
   static const int kMinLowLatencyFrameSize = 2048;
   int frames_per_buffer = std::min(
       std::max(input_params.frames_per_buffer(), kMinLowLatencyFrameSize),
       static_cast<int>(
           GetHighLatencyOutputBufferSize(input_params.sample_rate())));
 
   return AudioParameters(
       AudioParameters::AUDIO_PCM_LINEAR, input_params.channel_layout(),
       input_params.sample_rate(), input_params.bits_per_sample(),
       frames_per_buffer);
 }
+#endif
 
 AudioOutputResampler::AudioOutputResampler(AudioManager* audio_manager,
                                            const AudioParameters& input_params,
                                            const AudioParameters& output_params,
                                            const base::TimeDelta& close_delay)
     : AudioOutputDispatcher(audio_manager, input_params),
       close_delay_(close_delay),
       output_params_(output_params),
       streams_opened_(false) {
   DCHECK(input_params.IsValid());
@@ skipping 40 matching lines @@
 
   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_);
+
+  // Only Windows has a high latency output driver that is not the same as the
+  // low latency path.
+#if defined(OS_WIN)
+  DLOG(ERROR) << "Unable to open audio device in low latency mode.  Falling "
+              << "back to high latency audio output.";
+
   output_params_ = SetupFallbackParams(params_, output_params_);
   Initialize();
   if (dispatcher_->OpenStream()) {
     streams_opened_ = true;
     return true;
   }
+#endif
 
   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_.channels(), params_.input_channels(), params_.sample_rate(),
       params_.bits_per_sample(), params_.frames_per_buffer());
   Initialize();
@@ skipping 164 matching lines @@
     source_callback_->OnError(stream);
 }
 
 void OnMoreDataConverter::WaitTillDataReady() {
   base::AutoLock auto_lock(source_lock_);
   if (source_callback_)
     source_callback_->WaitTillDataReady();
 }
 
 }  // namespace media