Adding ArcBridge Interface for Volume Update Requests

components/arc/audio/arc_audio_bridge.cc

Index: components/arc/audio/arc_audio_bridge.cc
diff --git a/components/arc/audio/arc_audio_bridge.cc b/components/arc/audio/arc_audio_bridge.cc
index bdf7e4feafce96eb955d6e98bff5e3a6a36b2686..979d4b007fad58a483de3a682adc226ab31178e5 100644
--- a/components/arc/audio/arc_audio_bridge.cc
+++ b/components/arc/audio/arc_audio_bridge.cc
@@ -39,6 +39,14 @@ void ArcAudioBridge::ShowVolumeControls() {
   ash::TrayAudio::ShowPopUpVolumeView();
 }
 
+void ArcAudioBridge::OnVolumeUpdateRequest(float volume) {
+  cras_audio_handler_->SetOutputVolumePercent(volume);

[dcheng, 2017/04/14 03:36:42]

This should check that the input is in range.

(Out of curiosity, why a float and not an int?)

[yueli, 2017/06/02 19:10:13]

It seems the range is already handled in SetOutputNodeVolumePercent.
As for the float value, just want to provide the more accurate value. But since
we can only set volume by int, it also make sense to just send an int.

[dcheng, 2017/06/02 23:25:35]

This is OK, but I will note that it makes it a bit confusing when validation is
handled at different layers. I wouldn't have expected SetOuputNodeVolumePercent
to have to try to handle bad inputs gracefully, but I don't understand the CrOS
layering well enough to comment more.
I don't see any changes in this CL, does this comment mean that we're planning
on changing this to pass an int?

[yueli, 2017/06/06 16:43:09]

Done.

+  bool is_muted =
+      volume <= cras_audio_handler_->GetOutputDefaultVolumeMuteThreshold();
+  if (cras_audio_handler_->IsOutputMuted() != is_muted)
+    cras_audio_handler_->SetOutputMute(is_muted);
+}
+
 void ArcAudioBridge::OnAudioNodesChanged() {
   uint64_t output_id = cras_audio_handler_->GetPrimaryActiveOutputNode();
   const chromeos::AudioDevice* output_device =