ash: Start/stop observing KeyboardController via ShellObserver

ash/common/wm/lock_layout_manager.h

 // Copyright 2014 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.
 
 #ifndef ASH_COMMON_WM_LOCK_LAYOUT_MANAGER_H_
 #define ASH_COMMON_WM_LOCK_LAYOUT_MANAGER_H_
 
 #include "ash/ash_export.h"
 #include "ash/common/shell_observer.h"
 #include "ash/common/wm/wm_snap_to_pixel_layout_manager.h"
 #include "ash/common/wm/wm_types.h"
 #include "base/macros.h"
+#include "base/scoped_observer.h"
 #include "ui/aura/window_observer.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/keyboard/keyboard_controller.h"
 #include "ui/keyboard/keyboard_controller_observer.h"
 
 namespace ash {
 namespace wm {
 class WindowState;
 class WMEvent;
 }
@@ skipping 27 matching lines @@
   void SetChildBounds(WmWindow* child,
                       const gfx::Rect& requested_bounds) override;
 
   // Overriden from aura::WindowObserver:
   void OnWindowDestroying(aura::Window* window) override;
   void OnWindowBoundsChanged(aura::Window* window,
                              const gfx::Rect& old_bounds,
                              const gfx::Rect& new_bounds) override;
 
   // ShellObserver:
-  void OnVirtualKeyboardStateChanged(bool activated) override;
+  void OnVirtualKeyboardStateChanged(bool activated,
+                                     WmWindow* root_window) override;
 
   // keyboard::KeyboardControllerObserver overrides:
   void OnKeyboardBoundsChanging(const gfx::Rect& new_bounds) override;
   void OnKeyboardClosed() override;
 
  private:
   // Adjusts the bounds of all managed windows when the display area changes.
   // This happens when the display size, work area insets has changed.
   void AdjustWindowsForWorkAreaChange(const wm::WMEvent* event);
 
   WmWindow* window_;
   WmWindow* root_window_;
 
-  // True is subscribed as keyboard controller observer.
-  bool is_observing_keyboard_;
+  ScopedObserver<keyboard::KeyboardController,
+                 keyboard::KeyboardControllerObserver>
+      keyboard_observer_;
 
   // The bounds of the keyboard.
   gfx::Rect keyboard_bounds_;
 
   DISALLOW_COPY_AND_ASSIGN(LockLayoutManager);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_WM_LOCK_LAYOUT_MANAGER_H_