Implement "pinned" mode in ash.

ash/mus/bridge/wm_shell_mus.h

 // 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.
 
 #ifndef ASH_MUS_BRIDGE_WM_SHELL_MUS_H_
 #define ASH_MUS_BRIDGE_WM_SHELL_MUS_H_
 
 #include <stdint.h>
 
 #include <vector>
@@ skipping 35 matching lines @@
 
   // WmShell:
   MruWindowTracker* GetMruWindowTracker() override;
   WmWindow* NewContainerWindow() override;
   WmWindow* GetFocusedWindow() override;
   WmWindow* GetActiveWindow() override;
   WmWindow* GetPrimaryRootWindow() override;
   WmWindow* GetRootWindowForDisplayId(int64_t display_id) override;
   WmWindow* GetRootWindowForNewWindows() override;
   bool IsForceMaximizeOnFirstRun() override;
+  bool IsPinned() override;
+  void SetPinnedWindow(WmWindow* window) override;
   bool CanShowWindowForUser(WmWindow* window) override;
   void LockCursor() override;
   void UnlockCursor() override;
   std::vector<WmWindow*> GetAllRootWindows() override;
   void RecordUserMetricsAction(UserMetricsAction action) override;
   std::unique_ptr<WindowResizer> CreateDragWindowResizer(
       std::unique_ptr<WindowResizer> next_window_resizer,
       wm::WindowState* window_state) override;
   void OnOverviewModeStarting() override;
   void OnOverviewModeEnded() override;
   bool IsOverviewModeSelecting() override;
   bool IsOverviewModeRestoringMinimizedWindows() override;
   AccessibilityDelegate* GetAccessibilityDelegate() override;
   SessionStateDelegate* GetSessionStateDelegate() override;
   void AddActivationObserver(WmActivationObserver* observer) override;
   void RemoveActivationObserver(WmActivationObserver* observer) override;
   void AddDisplayObserver(WmDisplayObserver* observer) override;
   void RemoveDisplayObserver(WmDisplayObserver* observer) override;
   void AddShellObserver(ShellObserver* observer) override;
   void RemoveShellObserver(ShellObserver* observer) override;
-  void NotifyPinnedStateChanged(WmWindow* pinned_window) override;
 
  private:
   // Returns true if |window| is a window that can have active children.
   static bool IsActivationParent(::mus::Window* window);
 
   void RemoveClientObserver();
 
   // ::mus::WindowTreeClientObserver:
   void OnWindowTreeFocusChanged(::mus::Window* gained_focus,
                                 ::mus::Window* lost_focus) override;
@@ skipping 11 matching lines @@
 
   base::ObserverList<WmActivationObserver> activation_observers_;
 
   DISALLOW_COPY_AND_ASSIGN(WmShellMus);
 };
 
 }  // namespace mus
 }  // namespace ash
 
 #endif  // ASH_MUS_BRIDGE_WM_SHELL_MUS_H_