NTP: simplify mojo connection setup

chrome/browser/ui/search/search_ipc_router.h

 // Copyright 2013 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 CHROME_BROWSER_UI_SEARCH_SEARCH_IPC_ROUTER_H_
 #define CHROME_BROWSER_UI_SEARCH_SEARCH_IPC_ROUTER_H_
 
 #include <memory>
 #include <vector>
 
@@ skipping 219 matching lines @@
   Delegate* delegate_;
   std::unique_ptr<Policy> policy_;
 
   // Holds the number of main frame commits executed in this tab. Used by the
   // SearchIPCRouter to ensure that delayed IPC replies are ignored.
   int commit_counter_;
 
   // Set to true, when the tab corresponding to |this| instance is active.
   bool is_active_tab_;
 
-  content::WebContentsFrameBindingSet<chrome::mojom::Instant> bindings_;
+  // Binding for the connected main frame. We only allow one frame to connect at
+  // the moment, but this could be extended to a map of connected frames, if
+  // desired.
+  mojo::AssociatedBinding<chrome::mojom::Instant> binding_;
 
   std::unique_ptr<SearchBoxClientFactory> search_box_client_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(SearchIPCRouter);
 };
 
 #endif  // CHROME_BROWSER_UI_SEARCH_SEARCH_IPC_ROUTER_H_