Add WM_EVENT_TRUSTED_PIN and WINDOW_STATE_TYPE_TRUSTED_PINNED to Ash.

ash/accelerators/accelerator_controller_delegate_aura.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/accelerators/accelerator_controller_delegate_aura.h"
 
 #include <algorithm>
 #include <cmath>
 #include <string>
 #include <utility>
@@ skipping 295 matching lines @@
           wallpaper::WALLPAPER_LAYOUT_CENTER);
       break;
     case 3:
       desktop_background_controller->SetWallpaperImage(
           CreateWallpaperImage(SK_ColorGREEN, SK_ColorRED),
           wallpaper::WALLPAPER_LAYOUT_CENTER_CROPPED);
       break;
   }
 }
 
 bool CanHandleUnpin() {

[hidehiko, 2016/08/29 14:31:38]

Looks to work practically, but is it ok to leave UNPIN in the table?
https://cs.chromium.org/chromium/src/ash/common/accelerators/accelerator_tabl...

[hirono, 2016/08/30 07:16:08]

I tried to create a new list in accelerator_table.cc for trusted pin state 
after getting the comment. But now I feel like keeping the implementation as it
it.

The accelerator action list is referred by accelerator controller. And
accelerator controller accesses wm::Shell to get current shell state. However 
wm::Shell does not know the difference between trusted pinned and normal pinned,
which I'd like to keep hiding internally.

WDYT?

+  // Returns true only for WINDOW_STATE_TYPE_PINNED.
+  // WINDOW_STATE_TYPE_TRUSTED_PINNED does not accept user's unpin operation.
   wm::WindowState* window_state = wm::GetActiveWindowState();
-  return window_state && window_state->IsPinned();
+  return window_state &&
+         window_state->GetStateType() == wm::WINDOW_STATE_TYPE_PINNED;
 }
 
 #if defined(OS_CHROMEOS)
 void HandleSwapPrimaryDisplay() {
   base::RecordAction(UserMetricsAction("Accel_Swap_Primary_Display"));
   Shell::GetInstance()->display_configuration_controller()->SetPrimaryDisplayId(
       ScreenUtil::GetSecondaryDisplay().id(), true /* user_action */);
 }
 
 void HandleToggleMirrorMode() {
@@ skipping 315 matching lines @@
           message_center::NotifierId(
               message_center::NotifierId::SYSTEM_COMPONENT,
               system_notifier::kNotifierDeprecatedAccelerator),
           message_center::RichNotificationData(),
           new DeprecatedAcceleratorNotificationDelegate));
   message_center::MessageCenter::Get()->AddNotification(
       std::move(notification));
 }
 
 }  // namespace ash