Cleanup TrayCast with media-router only support in mind.

ash/common/system/chromeos/cast/tray_cast.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_COMMON_SYSTEM_CHROMEOS_CAST_TRAY_CAST_H_
 #define ASH_COMMON_SYSTEM_CHROMEOS_CAST_TRAY_CAST_H_
 
 #include "ash/common/cast_config_delegate.h"
 #include "ash/common/shell_observer.h"
 #include "ash/common/system/tray/system_tray_item.h"
@@ skipping 40 matching lines @@
   void OnDevicesUpdated(
       const CastConfigDelegate::SinksAndRoutes& devices) override;
 
   // This makes sure that the current view displayed in the tray is the correct
   // one, depending on if we are currently casting. If we're casting, then a
   // view with a stop button is displayed; otherwise, a view that links to a
   // detail view is displayed instead that allows the user to easily begin a
   // casting session.
   void UpdatePrimaryView();
 
+  // Returns true if there is an active cast route. The route may be DIAL based,
+  // such as casting YouTube where the cast sink directly streams content from
+  // another server. In that case, is_mirror_casting_ will be false since this
+  // device is not actively transmitting information to the cast sink.
+  bool HasActiveRoute();
+
   CastConfigDelegate::SinksAndRoutes sinks_and_routes_;
-  bool is_casting_ = false;
 
-  bool added_observer_ = false;
+  // True if there is a mirror-based cast session and the active-cast tray icon
+  // should be shown.
+  bool is_mirror_casting_ = false;
 
   // Not owned.
   tray::CastTrayView* tray_ = nullptr;
   tray::CastDuplexView* default_ = nullptr;
   tray::CastDetailedView* detailed_ = nullptr;
 
   DISALLOW_COPY_AND_ASSIGN(TrayCast);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_SYSTEM_CHROMEOS_CAST_TRAY_CAST_H_