Remove Chromecast extension support from cast system tray menu.

ash/common/system/cast/tray_cast.h

Index: ash/common/system/cast/tray_cast.h
diff --git a/ash/common/system/cast/tray_cast.h b/ash/common/system/cast/tray_cast.h
index 55d049b59c07dcddb985e0d015a12aedcbd2a1a9..7ff765420400257f2ef1dbec67c8d60d810b0fe5 100644
--- a/ash/common/system/cast/tray_cast.h
+++ b/ash/common/system/cast/tray_cast.h
@@ -50,10 +50,7 @@ class ASH_EXPORT TrayCast : public SystemTrayItem,
 
   // Overridden from CastConfigDelegate::Observer.
   void OnDevicesUpdated(
-      const CastConfigDelegate::ReceiversAndActivities& devices) override;
-
-  // Returns true if the cast extension was detected.
-  bool HasCastExtension();
+      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
@@ -62,10 +59,17 @@ class ASH_EXPORT TrayCast : public SystemTrayItem,
   // casting session.
   void UpdatePrimaryView();
 
-  CastConfigDelegate::ReceiversAndActivities receivers_and_activities_;
-  bool is_casting_ = false;
+  // 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 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;