Allow better AudioRendererMixer reuse by ignoring irrelevant params.

content/renderer/media/audio_renderer_mixer_manager.cc

Index: content/renderer/media/audio_renderer_mixer_manager.cc
diff --git a/content/renderer/media/audio_renderer_mixer_manager.cc b/content/renderer/media/audio_renderer_mixer_manager.cc
index 901807bad19e865da43a8d860cbb43a56ac0c015..4a62d1a15838ede9071ee57f590a28404b69e968 100644
--- a/content/renderer/media/audio_renderer_mixer_manager.cc
+++ b/content/renderer/media/audio_renderer_mixer_manager.cc
@@ -47,6 +47,9 @@ 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_);
 
@@ -66,7 +69,7 @@ media::AudioRendererMixer* AudioRendererMixerManager::GetMixer(
 
   // 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());