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 145e02e09dc89e72fcfa05781001ae4ea8a9e22a..c39209842d00a6311b36811e96fd9ed326952a56 100644
--- a/content/renderer/render_frame_impl.h
+++ b/content/renderer/render_frame_impl.h
@@ -552,6 +552,7 @@ 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;
@@ -1008,6 +1009,8 @@ 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_;