Content API changes to improve DOM stitching in ThreatDetails code.

content/browser/frame_host/render_frame_proxy_host.cc

Index: content/browser/frame_host/render_frame_proxy_host.cc
diff --git a/content/browser/frame_host/render_frame_proxy_host.cc b/content/browser/frame_host/render_frame_proxy_host.cc
index 1107e77fe4508b99b5a2f3446bf766bf59c7ad7d..b9a26c4613968c2f0c7a7799937388a9d44b4ed6 100644
--- a/content/browser/frame_host/render_frame_proxy_host.cc
+++ b/content/browser/frame_host/render_frame_proxy_host.cc
@@ -110,6 +110,10 @@ void RenderFrameProxyHost::SetChildRWHView(RenderWidgetHostView* view) {
       static_cast<RenderWidgetHostViewChildFrame*>(view));
 }
 
+int RenderFrameProxyHost::GetFrameTreeNodeId() const {
+  return frame_tree_node_->frame_tree_node_id();
+}
+
 RenderViewHostImpl* RenderFrameProxyHost::GetRenderViewHost() {
   return frame_tree_node_->frame_tree()->GetRenderViewHost(
       site_instance_.get());