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 6a12d344cf4e662c2368882f380ed6b82867c889..ce35a06902f86a83debbcb0e12afcff737dd8dd1 100644
--- a/chromeos/audio/cras_audio_handler.cc
+++ b/chromeos/audio/cras_audio_handler.cc
@@ -376,6 +376,13 @@ void CrasAudioHandler::SetOutputVolumePercent(int volume_percent) {
   }
 }
 
+void CrasAudioHandler::SetOutputVolumePercentWithoutNotifyingObservers(
+    int volume_percent,
+    AutomatedVolumeChangeReason reason) {
+  automated_volume_change_reasons_.push_back(reason);
+  SetOutputVolumePercent(volume_percent);
+}
+
 // 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?
@@ -613,27 +620,28 @@ void CrasAudioHandler::OutputNodeVolumeChanged(uint64_t node_id, int volume) {
   output_volume_ = volume;
   audio_pref_handler_->SetVolumeGainValue(*device, volume);
 
-  if (initializing_audio_state_) {
-    // Do not notify the observers for volume changed event if CrasAudioHandler
-    // is initializing its state, i.e., the volume change event is in responding
-    // to SetOutputNodeVolume request from intializaing audio state, not
-    // from user action, no need to notify UI to pop uo the volume slider bar.
-    if (init_node_id_ == node_id && init_volume_ == volume) {
-      init_volume_count_--;
-      if (!init_volume_count_)
-        initializing_audio_state_ = false;
-      return;
+  bool should_notify = true;
+  if (!automated_volume_change_reasons_.empty()) {
+    AutomatedVolumeChangeReason reason =
+        automated_volume_change_reasons_.front();
+    if (reason == VOLUME_CHANGE_INITIALIZING_AUDIO_STATE &&
+        (init_node_id_ != node_id || init_volume_ != volume)) {
+      // A SetOutputNodeVolume request may be dropped if cras isn't ready
+      // during initialization. In this case, we clear the pending automated
+      // volume change reasons as they might also be dropped by cras.
+      automated_volume_change_reasons_.clear();

[jennyz, 2016/08/02 18:02:33]

Can we add a warning log here for diagnostic purpose? Like LOG(WARNING) <<
"OutputNodeVolumeChanged signal dropped during the initialization. 

[Qiang(Joe) Xu, 2016/08/02 22:45:58]

Done.

     } else {
-      // Reset the initializing_audio_state_ in case SetOutputNodeVolume request
-      // is lost by cras due to cras is not ready when CrasAudioHandler is being
-      // initialized.
-      initializing_audio_state_ = false;
-      init_volume_count_ = 0;
+      // In other cases, sequential AutomatedVolumeChangeReason corresponds to
+      // sequential avoiding notifying observers.
+      should_notify = false;
+      automated_volume_change_reasons_.pop_front();
     }
   }
 
-  FOR_EACH_OBSERVER(AudioObserver, observers_,
-                    OnOutputNodeVolumeChanged(node_id, volume));
+  if (should_notify) {
+    FOR_EACH_OBSERVER(AudioObserver, observers_,
+                      OnOutputNodeVolumeChanged(node_id, volume));
+  }
 }
 
 void CrasAudioHandler::ActiveOutputNodeChanged(uint64_t node_id) {
@@ -738,12 +746,13 @@ void CrasAudioHandler::SetupAudioOutputState() {
 
   SetOutputMuteInternal(output_mute_on_);
 
-  if (initializing_audio_state_) {
+  if (!automated_volume_change_reasons_.empty() &&
+      automated_volume_change_reasons_.front() ==
+          VOLUME_CHANGE_INITIALIZING_AUDIO_STATE) {

[jennyz, 2016/08/02 18:02:33]

Will it be more straight forward by keeping initializing_audio_state_? It looks
better to keep the logic for pushing automated_volume_change_reasons_ and
SetOutputNodeVolume together.

if (initializing_audio_state_) 
  SetOutputVolumePercentWithoutNotifyingObservers(volume_percent,
VOLUME_CHANGE_INITIALIZING_AUDIO_STATE);

[Qiang(Joe) Xu, 2016/08/02 22:45:58]

It is great, thanks. In this way, automated_volume_change_reasons_ is pushed
only by SetOutputVolumePercentWithoutNotifyingObservers and poped only by
OutputNodeVolumeChanged. This makes the code cleaner.

     // During power up, InitializeAudioState() could be called twice, first
     // by CrasAudioHandler constructor, then by cras server restarting signal,
     // both sending SetOutputNodeVolume requests, and could lead to two
     // OutputNodeVolumeChanged signals.

[Daniel Erat, 2016/08/02 16:31:38]

i don't understand why you don't need to push another
VOLUME_CHANGE_INITIALIZING_AUDIO_STATE reason here. won't you get two signals
that you need to ignore?

[Qiang(Joe) Xu, 2016/08/02 22:45:58]

Yeah, I may change the code logic from jennyz's. I adopt the suggestion from
jennyz, which makes it cleaner and should have no problem then.

-    init_volume_count_++;
     init_node_id_ = active_output_node_id_;
     init_volume_ = output_volume_;
   }
@@ -774,7 +783,8 @@ void CrasAudioHandler::SetupAdditionalActiveAudioNodeState(uint64_t node_id) {
 }
 
 void CrasAudioHandler::InitializeAudioState() {
-  initializing_audio_state_ = true;
+  automated_volume_change_reasons_.push_back(
+      VOLUME_CHANGE_INITIALIZING_AUDIO_STATE);
   ApplyAudioPolicy();
 
   // Defer querying cras for GetNodes until cras service becomes available.