Fix Volume slider is captured in screenshot done in touchview mode

chromeos/audio/cras_audio_handler.cc

Index: chromeos/audio/cras_audio_handler.cc
diff --git a/chromeos/audio/cras_audio_handler.cc b/chromeos/audio/cras_audio_handler.cc
index a8f8036134ead71310d5a6748f4230045971f1f3..084a18aeba7a53127671baa76af8cc8c76b0b2b2 100644
--- a/chromeos/audio/cras_audio_handler.cc
+++ b/chromeos/audio/cras_audio_handler.cc
@@ -376,6 +376,17 @@ void CrasAudioHandler::SetOutputVolumePercent(int volume_percent) {
   }
 }
 
+void CrasAudioHandler::SetOutputVolumePercentInternally(int volume_percent) {

[jennyz, 2016/07/28 21:10:05]

Please add a unit test for this new API.

[Qiang(Joe) Xu, 2016/07/28 23:15:57]

Done.

+  volume_internally_changed_ = true;

[jennyz, 2016/07/28 21:02:17]

Will it be possible for SetOutputVolumePercentInternal be called multiple times
consecutively? If so, you may need to track its number. If not, please add some
DCHECK or Error log here.

[Qiang(Joe) Xu, 2016/07/28 23:15:57]

Currently only maximize mode screenshot calls this method. And I think everytime
screenshot is taken, the flag should already be released.

+  // Set all active devices to the same volume.
+  for (AudioDeviceMap::const_iterator it = audio_devices_.begin();
+       it != audio_devices_.end(); it++) {
+    const AudioDevice& device = it->second;
+    if (!device.is_input && device.active)
+      SetOutputNodeVolumePercent(device.id, volume_percent);
+  }

[jennyz, 2016/07/28 21:02:17]

line 381-387 is the same as SetOutputVolumePercent, why not just call
SetOutputVolumePercent?

[Qiang(Joe) Xu, 2016/07/28 23:15:57]

Done.

+}
+
 // TODO: Rename the 'Percent' to something more meaningful.
 void CrasAudioHandler::SetInputGainPercent(int gain_percent) {
   // TODO(jennyz): Should we set all input devices' gain to the same level?
@@ -632,6 +643,14 @@ void CrasAudioHandler::OutputNodeVolumeChanged(uint64_t node_id, int volume) {
     }
   }
 
+  // Do not notify the observers for the volume changed event if that is
+  // initiated internally, not by users. For example, a volume restoring
+  // comes from maximize mode screenshot volume-down, power down accelerators.
+  if (volume_internally_changed_) {

[jennyz, 2016/07/28 21:02:17]

volume_internally_changed_ is similar to initializing_audio_state_, can you
merge them?

[Qiang(Joe) Xu, 2016/07/28 23:15:57]

I use a mask to merge them.

+    volume_internally_changed_ = false;
+    return;
+  }
+
   FOR_EACH_OBSERVER(AudioObserver, observers_,
                     OnOutputNodeVolumeChanged(node_id, volume));
 }