Add the supporting code for the cast system tray integration

ash/system/tray/system_tray_delegate.h

 // Copyright (c) 2012 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_SYSTEM_TRAY_SYSTEM_TRAY_DELEGATE_H_
 #define ASH_SYSTEM_TRAY_SYSTEM_TRAY_DELEGATE_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 80 matching lines @@
   UpdateInfo();
   ~UpdateInfo();
 
   UpdateSeverity severity;
   bool update_required;
   bool factory_reset_required;
 };
 
 using IMEInfoList = std::vector<IMEInfo>;
 
+class CastConfigDelegate;
 class NetworkingConfigDelegate;
 class VPNDelegate;
 
 using RebootOnShutdownCallback = base::Callback<void(bool)>;
 
 namespace tray {
 class UserAccountsDelegate;
 }  // namespace tray
 
 // SystemTrayDelegate is intended for delegating tasks in the System Tray to the
@@ skipping 166 matching lines @@
 
   // Returns whether bluetooth is enabled.
   virtual bool GetBluetoothEnabled();
 
   // Returns whether the delegate has initiated a bluetooth discovery session.
   virtual bool GetBluetoothDiscovering();
 
   // Shows UI for changing proxy settings.
   virtual void ChangeProxySettings();
 
+  // Returns CastConfigDelegate. May return nullptr.
+  virtual CastConfigDelegate* GetCastConfigDelegate() const;
+
   // Returns NetworkingConfigDelegate. May return nullptr.
   virtual NetworkingConfigDelegate* GetNetworkingConfigDelegate() const;
 
   // Returns VolumeControlDelegate. May return nullptr.
   virtual VolumeControlDelegate* GetVolumeControlDelegate() const;
 
   // Sets the VolumeControlDelegate.
   virtual void SetVolumeControlDelegate(
       scoped_ptr<VolumeControlDelegate> delegate);
 
@@ skipping 37 matching lines @@
   // asynchronously calls |callback| once a trusted policy becomes available.
   virtual void ShouldRebootOnShutdown(const RebootOnShutdownCallback& callback);
 
   // Returns VPNDelegate. May return nullptr.
   virtual VPNDelegate* GetVPNDelegate() const;
 };
 
 }  // namespace ash
 
 #endif  // ASH_SYSTEM_TRAY_SYSTEM_TRAY_DELEGATE_H_