Consume Mojo services directly in Blink's WebUSB implementation.

content/renderer/render_frame_impl.h

Index: content/renderer/render_frame_impl.h
diff --git a/content/renderer/render_frame_impl.h b/content/renderer/render_frame_impl.h
index 9532978e5ed65e86f4d39293ddd3946147d7bd3c..e7894d547c243d11bc7653adfbea5c9db0326878 100644
--- a/content/renderer/render_frame_impl.h
+++ b/content/renderer/render_frame_impl.h
@@ -611,7 +611,6 @@ class CONTENT_EXPORT RenderFrameImpl
   void unregisterProtocolHandler(const blink::WebString& scheme,
                                  const blink::WebURL& url) override;
   blink::WebBluetooth* bluetooth() override;
-  blink::WebUSBClient* usbClient() override;
   void checkIfAudioSinkExistsAndIsAuthorized(
       const blink::WebString& sink_id,
       const blink::WebSecurityOrigin& security_origin,
@@ -1188,8 +1187,6 @@ class CONTENT_EXPORT RenderFrameImpl
 
   scoped_ptr<blink::WebBluetooth> bluetooth_;
 
-  scoped_ptr<blink::WebUSBClient> usb_client_;
-
   // Manages play, pause notifications for WebMediaPlayer implementations; its
   // lifetime is tied to the RenderFrame via the RenderFrameObserver interface.
   media::RendererWebMediaPlayerDelegate* media_player_delegate_;