Pipe the devTools FrameId from blink into the browser for headless

headless/lib/browser/headless_web_contents_impl.h

Index: headless/lib/browser/headless_web_contents_impl.h
diff --git a/headless/lib/browser/headless_web_contents_impl.h b/headless/lib/browser/headless_web_contents_impl.h
index 1dd6c6d6eb6ef03b0bea48312551ea0d565cf575..e3ff4ee4925f628fe1516cfa436638d92f117094 100644
--- a/headless/lib/browser/headless_web_contents_impl.h
+++ b/headless/lib/browser/headless_web_contents_impl.h
@@ -92,6 +92,14 @@ class HEADLESS_EXPORT HeadlessWebContentsImpl
     return window_tree_host_.get();
   }
 
+  // Returns the devtools frame id corresponding to the |frame_tree_node_id|, if
+  // any.  Note this relies on an IPC sent from blink during navigation.
+  std::string GetUntrustedDevToolsFrameIdForFrameTreeNodeId(
+      int process_id,
+      int frame_tree_node_id) const;
+
+  int GetRenderProcessId() const;
+
  private:
   // Takes ownership of |web_contents|.
   HeadlessWebContentsImpl(content::WebContents* web_contents,