Pipe the devTools FrameId from blink into the browser for headless

content/browser/frame_host/render_frame_host_impl.h

Index: content/browser/frame_host/render_frame_host_impl.h
diff --git a/content/browser/frame_host/render_frame_host_impl.h b/content/browser/frame_host/render_frame_host_impl.h
index b2e398fece22b74253a98f124d3241024dc2cd62..7de9f7ffed539423d95d179d5d41f473c9e95d58 100644
--- a/content/browser/frame_host/render_frame_host_impl.h
+++ b/content/browser/frame_host/render_frame_host_impl.h
@@ -615,6 +615,8 @@ class CONTENT_EXPORT RenderFrameHostImpl
     return has_focused_editable_element_;
   }
 
+  const std::string& devtools_frame_id() const { return devtools_frame_id_; }
+
   // Cancels any blocked request for the frame and its subframes.
   void CancelBlockedRequestsForFrame();
 
@@ -772,6 +774,7 @@ class CONTENT_EXPORT RenderFrameHostImpl
   void OnFocusedNodeChanged(bool is_editable_element,
                             const gfx::Rect& bounds_in_frame_widget);
   void OnSetHasReceivedUserGesture();
+  void OnSetDevToolsFrameId(const std::string& devtools_frame_id);
 
 #if BUILDFLAG(USE_EXTERNAL_POPUP_MENU)
   void OnShowPopup(const FrameHostMsg_ShowPopup_Params& params);
@@ -1184,6 +1187,8 @@ class CONTENT_EXPORT RenderFrameHostImpl
   std::unique_ptr<service_manager::InterfaceRegistry> java_interface_registry_;
 #endif
 
+  std::string devtools_frame_id_;
+
   // NOTE: This must be the last member.
   base::WeakPtrFactory<RenderFrameHostImpl> weak_ptr_factory_;