Fix Volume slider is captured in screenshot done in touchview mode

chromeos/audio/cras_audio_handler.cc

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chromeos/audio/cras_audio_handler.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 358 matching lines @@
   // 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);
   }
 }
 
+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?
   for (AudioDeviceMap::const_iterator it = audio_devices_.begin();
        it != audio_devices_.end();
        it++) {
     const AudioDevice& device = it->second;
     if (device.is_input && device.active)
       SetInputNodeGainPercent(active_input_node_id_, gain_percent);
   }
@@ skipping 217 matching lines @@
   }
 
   // Sync internal volume state and notify UI for the change. We trust cras
   // signal to report the volume state of the device, no matter which source
   // set the volume, i.e., volume could be set from non-chrome source, like
   // Bluetooth headset, etc. Assume all active output devices share a single
   // 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) {
   if (active_output_node_id_ == node_id)
     return;
 
   // Active audio output device should always be changed by chrome.
   // During system boot, cras may change active input to unknown device 0x1,
   // we don't need to log it, since it is not an valid device.
   if (GetDeviceFromId(node_id)) {
@@ skipping 84 matching lines @@
   if (hdmi_rediscovering_ && !IsHDMIPrimaryOutputDevice()) {
     VLOG(1) << "Mute the output during HDMI re-discovering grace period";
     output_mute_on_ = true;
   } else {
     output_mute_on_ = audio_pref_handler_->GetMuteValue(*device);
   }
   output_volume_ = audio_pref_handler_->GetOutputVolumeValue(device);
 
   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_;
   }
   SetOutputNodeVolume(active_output_node_id_, output_volume_);
 }
 
 // This sets up the state of an additional active node.
 void CrasAudioHandler::SetupAdditionalActiveAudioNodeState(uint64_t node_id) {
   const AudioDevice* device = GetDeviceFromId(node_id);
   if (!device) {
@@ skipping 10 matching lines @@
   // devices. For input devices, we don't restore their gain value so far.
   // TODO(jennyz): crbug.com/417418, track the status for the decison if
   // we should persist input gain value in prefs.
   if (!device->is_input) {
     audio_pref_handler_->SetMuteValue(*device, IsOutputMuted());
     SetOutputNodeVolumePercent(node_id, GetOutputVolumePercent());
   }
 }
 
 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.
   cras_service_available_ = false;
   chromeos::DBusThreadManager::Get()
       ->GetCrasAudioClient()
       ->WaitForServiceToBeAvailable(base::Bind(
           &CrasAudioHandler::InitializeAudioAfterCrasServiceAvailable,
           weak_ptr_factory_.GetWeakPtr()));
 }
@@ skipping 590 matching lines @@
                      hdmi_rediscover_grace_period_duration_in_ms_),
       this, &CrasAudioHandler::UpdateAudioAfterHDMIRediscoverGracePeriod);
 }
 
 void CrasAudioHandler::SetHDMIRediscoverGracePeriodForTesting(
     int duration_in_ms) {
   hdmi_rediscover_grace_period_duration_in_ms_ = duration_in_ms;
 }
 
 }  // namespace chromeos