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..be055fbce4dd0df021356207e893320eea1ab089 100644
--- a/chromeos/audio/cras_audio_handler.cc
+++ b/chromeos/audio/cras_audio_handler.cc
@@ -25,6 +25,11 @@ namespace chromeos {
 
 namespace {
 
+enum AutomatedVolumeChangeReason {
+  VOLUME_CHANGE_INITIALIZING_AUDIO_STATE = 1 << 0,
+  VOLUME_CHANGE_MAXIMIZE_MODE_SCREENSHOT = 1 << 1,
+};
+
 // Default value for unmuting, as a percent in the range [0, 100].
 // Used when sound is unmuted, but volume was less than kMuteThresholdPercent.
 const int kDefaultUnmuteVolumePercent = 4;
@@ -376,6 +381,16 @@ void CrasAudioHandler::SetOutputVolumePercent(int volume_percent) {
   }
 }
 
+void CrasAudioHandler::SetOutputVolumePercentWithoutNotifyingObservers(
+    int volume_percent) {
+  // Currently SetOutputVolumePercentInQuietMode is only called from
+  // maximize mode screenshot in PowerButtonController. Everytime this method
+  // is called, DCHECK if MAXIMIZE_MODE_SCREENSHOT is already released.
+  DCHECK(!(automated_volume_change_ & VOLUME_CHANGE_MAXIMIZE_MODE_SCREENSHOT));

[Daniel Erat, 2016/07/29 17:53:38]

this dcheck makes me nervous. if MAXIMIZE_MODE_SCREENSHOT is unset
asynchronously, how can you guarantee this won't be hit if e.g. the user takes
two screenshots very quickly?

[Qiang(Joe) Xu, 2016/07/29 18:58:23]

Your concern is reasonable. I am assuming CRAS is reliable and does not have a
large delay. We can use a counter so that multiple quick screenshot still works
properly.

+  automated_volume_change_ |= VOLUME_CHANGE_MAXIMIZE_MODE_SCREENSHOT;
+  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 +628,38 @@ void CrasAudioHandler::OutputNodeVolumeChanged(uint64_t node_id, int volume) {
   output_volume_ = volume;
   audio_pref_handler_->SetVolumeGainValue(*device, volume);
 
-  if (initializing_audio_state_) {
+  bool should_not_notify_observers = false;
+  if (automated_volume_change_ & VOLUME_CHANGE_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.
+    // to SetOutputNodeVolume request from intializaing audio state, not from

[Daniel Erat, 2016/07/29 17:53:38]

nit: s/intializaing/initializing/

[Qiang(Joe) Xu, 2016/07/29 18:58:23]

Done.

+    // user action, no need to notify UI to pop up 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;
+        automated_volume_change_ ^= VOLUME_CHANGE_INITIALIZING_AUDIO_STATE;
+      should_not_notify_observers = true;
     } 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;
+      // Reset the INITIALIZING_AUDIO_STATE in case SetOutputNodeVolume request
+      // is lost by cras due to cras is not ready when CrasAudioHandler is
+      // being initialized.
+      automated_volume_change_ ^= VOLUME_CHANGE_INITIALIZING_AUDIO_STATE;
       init_volume_count_ = 0;
     }
   }
 
-  FOR_EACH_OBSERVER(AudioObserver, observers_,
-                    OnOutputNodeVolumeChanged(node_id, volume));
+  if (automated_volume_change_ & VOLUME_CHANGE_MAXIMIZE_MODE_SCREENSHOT) {
+    // Do not notify the observers for the volume changed event if that is
+    // coming from a restoring volume after a maximize mode screenshot is
+    // taken. Reset the MAXIMIZE_MODE_SCREENSHOT.
+    automated_volume_change_ ^= VOLUME_CHANGE_MAXIMIZE_MODE_SCREENSHOT;
+    should_not_notify_observers = true;
+  }
+
+  if (!should_not_notify_observers) {
+    FOR_EACH_OBSERVER(AudioObserver, observers_,
+                      OnOutputNodeVolumeChanged(node_id, volume));
+  }
 }
 
 void CrasAudioHandler::ActiveOutputNodeChanged(uint64_t node_id) {
@@ -738,7 +764,7 @@ void CrasAudioHandler::SetupAudioOutputState() {
 
   SetOutputMuteInternal(output_mute_on_);
 
-  if (initializing_audio_state_) {
+  if (automated_volume_change_ & VOLUME_CHANGE_INITIALIZING_AUDIO_STATE) {
     // 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
@@ -774,7 +800,7 @@ void CrasAudioHandler::SetupAdditionalActiveAudioNodeState(uint64_t node_id) {
 }
 
 void CrasAudioHandler::InitializeAudioState() {
-  initializing_audio_state_ = true;
+  automated_volume_change_ |= VOLUME_CHANGE_INITIALIZING_AUDIO_STATE;
   ApplyAudioPolicy();
 
   // Defer querying cras for GetNodes until cras service becomes available.