Ignore OnKeyEvent for VKEY_POWER because it is handled by PowerButtonEvent

ash/system/chromeos/power/tablet_power_button_controller.cc

 // Copyright 2016 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 "ash/system/chromeos/power/tablet_power_button_controller.h"
 
 #include "ash/common/session/session_state_delegate.h"
 #include "ash/common/wm/maximize_mode/maximize_mode_controller.h"
 #include "ash/common/wm_shell.h"
 #include "ash/shell.h"
@@ skipping 120 matching lines @@
                                                     bool user_initiated) {
   brightness_level_is_zero_ = level == 0;
 }
 
 void TabletPowerButtonController::SuspendDone(
     const base::TimeDelta& sleep_duration) {
   last_resume_time_ = tick_clock_->NowTicks();
 }
 
 void TabletPowerButtonController::OnKeyEvent(ui::KeyEvent* event) {
+  if (event->key_code() == ui::VKEY_POWER)

[Daniel Erat, 2016/11/22 00:48:19]

please also document why these are ignored. something like this is fine:

  // Ignore key events generated by the power button since
  // power button activity is already handled by OnPowerButtonEvent().

[Qiang(Joe) Xu, 2016/11/22 01:02:50]

Done.

+    return;
+
   if (!IsTabletModeActive() && backlights_forced_off_)
     SetBacklightsForcedOff(false);
 }
 
 void TabletPowerButtonController::OnMouseEvent(ui::MouseEvent* event) {
   ui::EventPointerType pointer_type = event->pointer_details().pointer_type;
 
   if (pointer_type != ui::EventPointerType::POINTER_TYPE_MOUSE ||
       (event->flags() & ui::EF_IS_SYNTHESIZED)) {
     return;
@@ skipping 54 matching lines @@
       WmShell::Get()->GetSessionStateDelegate();
   if (session_state_delegate->ShouldLockScreenAutomatically() &&
       session_state_delegate->CanLockScreen() &&
       !session_state_delegate->IsUserSessionBlocked() &&
       !controller_->LockRequested()) {
     session_state_delegate->LockScreen();
   }
 }
 
 }  // namespace ash