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 8f370dbc10cbc9cc66fa5a013622df09cc71c10e..b674fe7dd3b99f816e6f9554f55f6ec9f6d30310 100644
--- a/third_party/WebKit/public/web/WebFrameClient.h
+++ b/third_party/WebKit/public/web/WebFrameClient.h
@@ -270,6 +270,9 @@ 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.