mash: Move SystemTrayDelegate ownership to WmShell

ash/common/wm_shell.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_COMMON_WM_SHELL_H_
 #define ASH_COMMON_WM_SHELL_H_
 
 #include <stdint.h>
 
 #include <memory>
 #include <vector>
 
 #include "ash/ash_export.h"
 
 namespace gfx {
 class Rect;
 }
 
 namespace ash {
 
 class AccessibilityDelegate;
 class MruWindowTracker;
 class SessionStateDelegate;
+class Shell;

[msw, 2016/06/10 20:48:10]

nit: needed?

 class ShellObserver;
+class SystemTrayDelegate;
 class WindowResizer;
 class WmActivationObserver;
 class WmDisplayObserver;
 class WmWindow;
 
 namespace wm {
 
 class WindowState;
 
 enum class WmUserMetricsAction;
 }
 
 // Similar to ash::Shell. Eventually the two will be merged.
 class ASH_EXPORT WmShell {
  public:
   // This is necessary for a handful of places that is difficult to plumb
   // through context.
   static void Set(WmShell* instance);
   static WmShell* Get();
   static bool HasInstance() { return instance_ != nullptr; }
 
+  SystemTrayDelegate* system_tray_delegate() {
+    return system_tray_delegate_.get();
+  }
+
   virtual MruWindowTracker* GetMruWindowTracker() = 0;
 
   // Creates a new window used as a container of other windows. No painting is
   // done to the created window.
   virtual WmWindow* NewContainerWindow() = 0;
 
   virtual WmWindow* GetFocusedWindow() = 0;
   virtual WmWindow* GetActiveWindow() = 0;
 
   virtual WmWindow* GetPrimaryRootWindow() = 0;
@@ skipping 52 matching lines @@
   virtual void AddActivationObserver(WmActivationObserver* observer) = 0;
   virtual void RemoveActivationObserver(WmActivationObserver* observer) = 0;
 
   virtual void AddDisplayObserver(WmDisplayObserver* observer) = 0;
   virtual void RemoveDisplayObserver(WmDisplayObserver* observer) = 0;
 
   virtual void AddShellObserver(ShellObserver* observer) = 0;
   virtual void RemoveShellObserver(ShellObserver* observer) = 0;
 
  protected:
-  virtual ~WmShell() {}
+  WmShell();
+  virtual ~WmShell();
+
+  // If |delegate| is not null, sets and initializes the delegate. If |delegate|
+  // is null, shuts down and destroys the delegate.
+  void SetSystemTrayDelegate(std::unique_ptr<SystemTrayDelegate> delegate);
 
  private:
+  friend class Shell;
+
   static WmShell* instance_;
+
+  std::unique_ptr<SystemTrayDelegate> system_tray_delegate_;
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_WM_SHELL_H_