[Media Router] Adds a contextual menu item to remove the MR component action.

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 c2ba29896b4312af296ac06df334efd91de26029..01637e80c5ee549a4b754f4f9a5d4178a6d1e99f 100644
--- a/chrome/browser/ui/toolbar/toolbar_actions_model.h
+++ b/chrome/browser/ui/toolbar/toolbar_actions_model.h
@@ -165,6 +165,10 @@ class ToolbarActionsModel
     return is_highlighting() ? highlighted_items_ : toolbar_items_;
   }
 
+  extensions::ComponentMigrationHelper* component_migration_helper() {
+    return component_migration_helper_.get();
+  }
+
   bool is_highlighting() const { return highlight_type_ != HIGHLIGHT_NONE; }
   HighlightType highlight_type() const { return highlight_type_; }
   bool highlighting_for_toolbar_redesign() const {