Pipe the devTools FrameId from blink into the browser for headless

content/browser/frame_host/render_frame_host_impl.cc

Index: content/browser/frame_host/render_frame_host_impl.cc
diff --git a/content/browser/frame_host/render_frame_host_impl.cc b/content/browser/frame_host/render_frame_host_impl.cc
index a64bf5be64a3f025792bea402a8d7eb096f1e680..c603dfcbe3d40e2d88e3dff22d62e8b6c867a2a8 100644
--- a/content/browser/frame_host/render_frame_host_impl.cc
+++ b/content/browser/frame_host/render_frame_host_impl.cc
@@ -811,6 +811,7 @@ bool RenderFrameHostImpl::OnMessageReceived(const IPC::Message &msg) {
     IPC_MESSAGE_HANDLER(FrameHostMsg_FocusedNodeChanged, OnFocusedNodeChanged)
     IPC_MESSAGE_HANDLER(FrameHostMsg_SetHasReceivedUserGesture,
                         OnSetHasReceivedUserGesture)
+    IPC_MESSAGE_HANDLER(FrameHostMsg_SetDevToolsFrameId, OnSetDevToolsFrameId)
 #if BUILDFLAG(USE_EXTERNAL_POPUP_MENU)
     IPC_MESSAGE_HANDLER(FrameHostMsg_ShowPopup, OnShowPopup)
     IPC_MESSAGE_HANDLER(FrameHostMsg_HidePopup, OnHidePopup)
@@ -2403,6 +2404,11 @@ void RenderFrameHostImpl::OnSetHasReceivedUserGesture() {
   frame_tree_node_->OnSetHasReceivedUserGesture();
 }
 
+void RenderFrameHostImpl::OnSetDevToolsFrameId(
+    const std::string& devtools_frame_id) {
+  devtools_frame_id_ = devtools_frame_id;

[Charlie Reis, 2017/04/24 20:26:42]

I'm a bit uncomfortable having the browser process make decisions on frame IDs
based on a value sent up by a potentially compromised renderer process.

I don't think this a good approach for people to be building code on top of.  If
it's needed as a stopgap until we solve the problem of passing FrameTreeNodes to
the renderer, then we at least need to make it clear that it's dangerous and
shouldn't be used by other code.

+}
+
 #if BUILDFLAG(USE_EXTERNAL_POPUP_MENU)
 void RenderFrameHostImpl::OnShowPopup(
     const FrameHostMsg_ShowPopup_Params& params) {