Fix Volume slider is captured in screenshot done in touchview mode

ash/wm/power_button_controller.cc

Index: ash/wm/power_button_controller.cc
diff --git a/ash/wm/power_button_controller.cc b/ash/wm/power_button_controller.cc
index 73c686a403a69604803a88b1728c503c1bbe8d84..93d082b6e1a87a1c23e95478772075285b0ac68e 100644
--- a/ash/wm/power_button_controller.cc
+++ b/ash/wm/power_button_controller.cc
@@ -8,27 +8,36 @@
 #include "ash/common/ash_switches.h"
 #include "ash/common/session/session_state_delegate.h"
 #include "ash/common/shell_window_ids.h"
+#include "ash/common/system/tray/system_tray_notifier.h"
 #include "ash/common/wm/maximize_mode/maximize_mode_controller.h"
 #include "ash/common/wm_shell.h"
 #include "ash/shell.h"
 #include "ash/wm/lock_state_controller.h"
 #include "ash/wm/session_state_animator.h"
 #include "base/command_line.h"
+#include "base/task_runner.h"
+#include "base/threading/thread_task_runner_handle.h"
 #include "ui/aura/window_event_dispatcher.h"
 #include "ui/display/types/display_snapshot.h"
 #include "ui/events/event_handler.h"
 #include "ui/wm/core/compound_event_filter.h"
 
 #if defined(OS_CHROMEOS)
+#include "chromeos/audio/cras_audio_handler.h"
 #include "chromeos/dbus/dbus_thread_manager.h"
 #endif
 
 namespace ash {
 
+namespace {
+const int kWaitVolumeSliderHiddenInMs = 200;

[Daniel Erat, 2016/07/28 04:45:00]

this isn't good; it means there's a delay between when the user requests the
screenshot and when we take it. how long does it actually take for the volume
slider to be hidden? is there an animation that you're waiting for? if so, can
you skip the animation? or is the problem that you're waiting for the screen to
be redrawn?

[Qiang(Joe) Xu, 2016/07/28 20:25:02]

done by disable hiding animation.

+}  // namespace
+
 PowerButtonController::PowerButtonController(LockStateController* controller)
     : power_button_down_(false),
       lock_button_down_(false),
       volume_down_pressed_(false),
+      saved_volume_percent_(0),
       brightness_is_zero_(false),
       internal_display_off_and_external_display_on_(false),
       has_legacy_power_button_(
@@ -80,9 +89,24 @@ void PowerButtonController::OnPowerButtonEvent(
       WmShell::Get()
           ->maximize_mode_controller()
           ->IsMaximizeModeWindowManagerEnabled()) {
-    WmShell::Get()->accelerator_controller()->PerformActionIfEnabled(
-        TAKE_SCREENSHOT);
+    // Notify that maximize mode screenshot is going to be taken. Receiver does
+    // preparation work.
+    WmShell::Get()
+        ->system_tray_notifier()
+        ->NotifyWillTakeScreenshotInMaximizeMode();
+    base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
+        FROM_HERE, base::Bind(&PowerButtonController::TakingScreenshot,
+                              base::Unretained(this)),
+        base::TimeDelta::FromMilliseconds(kWaitVolumeSliderHiddenInMs));
     return;
+
+#if defined(OS_CHROMEOS)
+    // Restore volume.
+    chromeos::CrasAudioHandler* audio_handler =
+        chromeos::CrasAudioHandler::Get();
+    DCHECK(audio_handler->IsInitialized());

[Daniel Erat, 2016/07/28 04:45:00]

you don't need this; Get() on the previous line already has a CHECK() that it's
initialized

[Qiang(Joe) Xu, 2016/07/28 20:25:02]

Done.

+    audio_handler->SetOutputVolumePercent(saved_volume_percent_);
+#endif
   }
 
   const SessionStateDelegate* session_state_delegate =
@@ -151,8 +175,18 @@ void PowerButtonController::OnLockButtonEvent(
 }
 
 void PowerButtonController::OnKeyEvent(ui::KeyEvent* event) {
-  if (event->key_code() == ui::VKEY_VOLUME_DOWN)
+  if (event->key_code() == ui::VKEY_VOLUME_DOWN) {
     volume_down_pressed_ = event->type() == ui::ET_KEY_PRESSED;
+#if defined(OS_CHROMEOS)
+    // Avoid saving to |saved_volume_percent_| if that is repeated pressing.

[Daniel Erat, 2016/07/28 04:45:00]

nit: delete this comment; the code is self-explanatory

+    if (!event->is_repeat()) {
+      chromeos::CrasAudioHandler* audio_handler =
+          chromeos::CrasAudioHandler::Get();
+      DCHECK(audio_handler->IsInitialized());

[Daniel Erat, 2016/07/28 04:45:00]

delete this too

+      saved_volume_percent_ = audio_handler->GetOutputVolumePercent();
+    }
+#endif
+  }
 }
 
 #if defined(OS_CHROMEOS)
@@ -179,4 +213,9 @@ void PowerButtonController::PowerButtonEventReceived(
 }
 #endif  // defined(OS_CHROMEOS)
 
+void PowerButtonController::TakingScreenshot() {
+  WmShell::Get()->accelerator_controller()->PerformActionIfEnabled(
+      TAKE_SCREENSHOT);
+}
+
 }  // namespace ash