mash: Move system tray cast code into //ash/common

ash/common/cast_config_delegate.h

 // Copyright 2015 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_CAST_CONFIG_DELEGATE_H_
-#define ASH_CAST_CONFIG_DELEGATE_H_
+#ifndef ASH_COMMON_CAST_CONFIG_DELEGATE_H_
+#define ASH_COMMON_CAST_CONFIG_DELEGATE_H_
 
 #include <memory>
 #include <string>
 #include <vector>
 
 #include "ash/ash_export.h"
 #include "base/macros.h"
 #include "base/strings/string16.h"
 #include "url/gurl.h"
 
@@ skipping 97 matching lines @@
   // Add or remove an observer.
   virtual void AddObserver(Observer* observer) = 0;
   virtual void RemoveObserver(Observer* observer) = 0;
 
  private:
   DISALLOW_ASSIGN(CastConfigDelegate);
 };
 
 }  // namespace ash
 
-#endif  // ASH_CAST_CONFIG_DELEGATE_H_
+#endif  // ASH_COMMON_CAST_CONFIG_DELEGATE_H_