mash: Add SystemTrayClient interface, use to show date settings

chrome/browser/ui/ash/system_tray_client.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 CHROME_BROWSER_UI_ASH_SYSTEM_TRAY_CONTROLLER_MUS_H_
-#define CHROME_BROWSER_UI_ASH_SYSTEM_TRAY_CONTROLLER_MUS_H_
+#ifndef CHROME_BROWSER_UI_ASH_SYSTEM_TRAY_CLIENT_H_
+#define CHROME_BROWSER_UI_ASH_SYSTEM_TRAY_CLIENT_H_
 
 #include "ash/public/interfaces/system_tray.mojom.h"
 #include "base/macros.h"
 #include "chrome/browser/chromeos/system/system_clock_observer.h"
+#include "mojo/public/cpp/bindings/binding.h"
 
-// Controls chrome's interaction with the ash system tray menu.
-class SystemTrayControllerMus : public chromeos::system::SystemClockObserver {
+// Handles method calls delegated back to chrome from ash. Also notifies ash of
+// relevant state changes in chrome.
+class SystemTrayClient : public ash::mojom::SystemTrayClient,

[James Cook, 2016/09/22 23:19:18]

I went with this class being SystemTrayClient because that seemed like the
convention from WindowTree. However, I could also go with SystemTrayClientMus to
emphasize this only exists for mustash.

[sky, 2016/09/23 16:42:26]

What you have SGTM.

+                         public chromeos::system::SystemClockObserver {
  public:
-  SystemTrayControllerMus();
-  ~SystemTrayControllerMus() override;
+  SystemTrayClient();
+  ~SystemTrayClient() override;
 
  private:
+  // ash::mojom::SystemTrayClient:
+  void ShowDateSettings() override;
+
   // chromeos::system::SystemClockObserver:
   void OnSystemClockChanged(chromeos::system::SystemClock* clock) override;
 
+  // System tray mojo service in ash.
   ash::mojom::SystemTrayPtr system_tray_;
 
-  DISALLOW_COPY_AND_ASSIGN(SystemTrayControllerMus);
+  // Binds the SystemTrayClient mojo interface to this object.
+  mojo::Binding<ash::mojom::SystemTrayClient> binding_;

[James Cook, 2016/09/22 23:19:18]

Is this the right binding type?

[sky, 2016/09/23 16:42:26]

The other one you could use is StrongBinding. StrongBinding owns the
implementation though (SystemTrayClient here). As you have
ChromeBrowserMainExtraPartsAsh owning SystemTrayClient you don't want
StrongBinding. In other words what you have is right for this case.

+
+  DISALLOW_COPY_AND_ASSIGN(SystemTrayClient);
 };
 
-#endif  // CHROME_BROWSER_UI_ASH_SYSTEM_TRAY_CONTROLLER_MUS_H_
+#endif  // CHROME_BROWSER_UI_ASH_SYSTEM_TRAY_CLIENT_H_