Allow better AudioRendererMixer reuse by ignoring irrelevant params.

content/renderer/media/audio_renderer_mixer_manager.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_renderer_mixer_manager.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "content/renderer/media/audio_device_factory.h"
 #include "media/audio/audio_output_device.h"
@@ skipping 29 matching lines @@
 
 void AudioRendererMixerManager::SetAudioRendererSinkForTesting(
     media::AudioRendererSink* sink) {
   sink_for_testing_ = sink;
 }
 
 media::AudioRendererMixer* AudioRendererMixerManager::GetMixer(
     int source_render_view_id,
     int source_render_frame_id,
     const media::AudioParameters& params) {
+  // Effects are not passed through to output creation, so ensure none are set.
+  DCHECK_EQ(params.effects(), media::AudioParameters::NO_EFFECTS);
+
   const MixerKey key(source_render_view_id, params);
   base::AutoLock auto_lock(mixers_lock_);
 
   AudioRendererMixerMap::iterator it = mixers_.find(key);
   if (it != mixers_.end()) {
     it->second.ref_count++;
     return it->second.mixer;
   }
 
   // On ChromeOS we can rely on the playback device to handle resampling, so
   // don't waste cycles on it here.
 #if defined(OS_CHROMEOS)
   int sample_rate = params.sample_rate();
 #else
   int sample_rate = hardware_config_->GetOutputSampleRate();
 #endif
 
   // Create output parameters based on the audio hardware configuration for
   // passing on to the output sink.  Force to 16-bit output for now since we
-  // know that works well for WebAudio and WebRTC.
+  // know that works everywhere; ChromeOS does not support other bit depths.
   media::AudioParameters output_params(
       media::AudioParameters::AUDIO_PCM_LOW_LATENCY, params.channel_layout(),
       sample_rate, 16, hardware_config_->GetHighLatencyBufferSize());
 
   // If we've created invalid output parameters, simply pass on the input params
   // and let the browser side handle automatic fallback.
   if (!output_params.IsValid())
     output_params = params;
 
   media::AudioRendererMixer* mixer;
@@ skipping 22 matching lines @@
 
   // Only remove the mixer if AudioRendererMixerManager is the last owner.
   it->second.ref_count--;
   if (it->second.ref_count == 0) {
     delete it->second.mixer;
     mixers_.erase(it);
   }
 }
 
 }  // namespace content