Add WebUSB bindings and client interface

public/web/WebFrameClient.h

 /*
  * Copyright (C) 2011, 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 71 matching lines @@
 class WebSocketHandle;
 class WebPlugin;
 class WebPluginPlaceholder;
 class WebPresentationClient;
 class WebPushClient;
 class WebRTCPeerConnectionHandler;
 class WebScreenOrientationClient;
 class WebString;
 class WebURL;
 class WebURLResponse;
+class WebUSBClient;
 class WebUserMediaClient;
 class WebVRClient;
 class WebWorkerContentSettingsClientProxy;
 struct WebColorSuggestion;
 struct WebConsoleMessage;
 struct WebContextMenuData;
 struct WebPluginParams;
 struct WebPopupMenuInfo;
 struct WebRect;
 struct WebURLError;
@@ skipping 556 matching lines @@
 
     // Check if a given URL handler is registered for the given protocol.
     virtual WebCustomHandlersState isProtocolHandlerRegistered(const WebString& scheme, const WebURL& url)
     {
         return WebCustomHandlersNew;
     }
 
     // Bluetooth -----------------------------------------------------------
     virtual WebBluetooth* bluetooth() { return 0; }
 
+    // WebUSB --------------------------------------------------------------
+    virtual WebUSBClient* usbClient() { return 0; }
+
 protected:
     virtual ~WebFrameClient() { }
 };
 
 } // namespace blink
 
 #endif