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>
 #include <cmath>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/logging.h"
 #include "base/sys_info.h"
 #include "base/system_monitor/system_monitor.h"
 #include "chromeos/audio/audio_devices_pref_handler_stub.h"
 #include "chromeos/dbus/dbus_thread_manager.h"
 
 using std::max;
 using std::min;
 
 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;
 
 // Volume value which should be considered as muted in range [0, 100].
 const int kMuteThresholdPercent = 1;
 
 // The duration of HDMI output re-discover grace period in milliseconds.
 const int kHDMIRediscoverGracePeriodDurationInMs = 2000;
 
@@ skipping 331 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) {
+  // 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?
   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_) {
+  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) {
   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_ & 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
     // OutputNodeVolumeChanged signals.
     init_volume_count_++;
     init_node_id_ = active_output_node_id_;
     init_volume_ = output_volume_;
   }
   SetOutputNodeVolume(active_output_node_id_, output_volume_);
 }
@@ skipping 15 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_ |= 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 584 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