Pipe the devTools FrameId from blink into the browser for headless

third_party/WebKit/public/web/WebFrameClient.h

Index: third_party/WebKit/public/web/WebFrameClient.h
diff --git a/third_party/WebKit/public/web/WebFrameClient.h b/third_party/WebKit/public/web/WebFrameClient.h
index beb961ee48304afe540b5eea3ef11f7c563e2326..1ab45e9f1fdb4f9782438a597ad4a8ef94c4d193 100644
--- a/third_party/WebKit/public/web/WebFrameClient.h
+++ b/third_party/WebKit/public/web/WebFrameClient.h
@@ -257,6 +257,9 @@ class BLINK_EXPORT WebFrameClient {
   // Called the first time this frame is the target of a user gesture.
   virtual void SetHasReceivedUserGesture() {}
 
+  // Notification of the devtools id for this frame.
+  virtual void SetDevToolsFrameId(const blink::WebString& devtools_frame_id) {}
+
   // Console messages ----------------------------------------------------
 
   // Whether or not we should report a detailed message for the given source.