Remove Chromecast extension support from cast system tray menu.

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 33 matching lines @@
   void DestroyDefaultView() override;
   void DestroyDetailedView() override;
 
   // Overridden from ShellObserver.
   void OnCastingSessionStartedOrStopped(bool started) override;
 
   // Overridden from CastConfigDelegate::Observer.
   void OnDevicesUpdated(
       const CastConfigDelegate::ReceiversAndActivities& devices) override;
 
-  // Returns true if the cast extension was detected.
-  bool HasCastExtension();
-
   // 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();
 
   CastConfigDelegate::ReceiversAndActivities receivers_and_activities_;
   bool is_casting_ = false;
 
   bool added_observer_ = 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_