Put the RenderFrame's ID into a per-frame WebBluetooth, and plumb that back to the browser.

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 fee7a623d2311812583cce2397fc91c51592a1a2..5e0549f18ad35347a406aa597fa084b74703a54b 100644
--- a/content/renderer/render_frame_impl.h
+++ b/content/renderer/render_frame_impl.h
@@ -546,6 +546,7 @@ class CONTENT_EXPORT RenderFrameImpl
                                        const blink::WebString& title);
   virtual void unregisterProtocolHandler(const blink::WebString& scheme,
                                          const blink::WebURL& url);
+  virtual blink::WebBluetooth* bluetooth();
 
 #if defined(ENABLE_WEBVR)
   blink::WebVRClient* webVRClient() override;
@@ -1002,6 +1003,8 @@ class CONTENT_EXPORT RenderFrameImpl
 
   scoped_ptr<blink::WebAppBannerClient> app_banner_client_;
 
+  scoped_ptr<blink::WebBluetooth> bluetooth_;
+
 #if defined(ENABLE_WEBVR)
   // The VR dispatcher attached to the frame, lazily initialized.
   scoped_ptr<VRDispatcher> vr_dispatcher_;