Show the Cast toolbar icon ephemerally when Cast is in use

chrome/browser/ui/toolbar/toolbar_actions_model.h

Index: chrome/browser/ui/toolbar/toolbar_actions_model.h
diff --git a/chrome/browser/ui/toolbar/toolbar_actions_model.h b/chrome/browser/ui/toolbar/toolbar_actions_model.h
index b8b99d536d65d794271752be8f3c83fc5d9e60fa..c5fc84c7972fff1109330abdb36d8fc92339ab2b 100644
--- a/chrome/browser/ui/toolbar/toolbar_actions_model.h
+++ b/chrome/browser/ui/toolbar/toolbar_actions_model.h
@@ -258,12 +258,11 @@ class ToolbarActionsModel
   bool HasItem(const ToolbarItem& item) const;
 
   // Adds |item| to the toolbar.  If the item has an existing preference for
-  // toolbar position, that will be used to determine its location.  If
-  // |is_component| is true, the item will be given a default postion of 0,
-  // otherwise the default is at the end of the visible items. If the toolbar is
-  // in highlighting mode, the item will not be visible until highlighting mode
-  // is exited.
-  void AddItem(const ToolbarItem& item, bool is_component);
+  // toolbar position, that will be used to determine its location. Otherwise
+  // it will be placed at the end of the visible items. If the toolbar is in
+  // highlighting mode, the item will not be visible until highlighting mode is
+  // exited.
+  void AddItem(const ToolbarItem& item);
 
   // Removes |item| from the toolbar.  If the toolbar is in highlighting mode,
   // the item is also removed from the highlighted list (if present).