Require a process ID when looking up RFHs by FrameTreeNode ID.

content/browser/frame_host/navigation_handle_impl.cc

Index: content/browser/frame_host/navigation_handle_impl.cc
diff --git a/content/browser/frame_host/navigation_handle_impl.cc b/content/browser/frame_host/navigation_handle_impl.cc
index 37f1c0c581746f799c9578ace7b1a76f98236dcb..968881e2b5450fe94c7f9cf355459c683153a3eb 100644
--- a/content/browser/frame_host/navigation_handle_impl.cc
+++ b/content/browser/frame_host/navigation_handle_impl.cc
@@ -237,6 +237,13 @@ int NavigationHandleImpl::GetParentFrameTreeNodeId() {
   return frame_tree_node_->parent()->frame_tree_node_id();
 }
 
+RenderFrameHostImpl* NavigationHandleImpl::GetParentFrame() {
+  if (frame_tree_node_->IsMainFrame())
+    return nullptr;
+
+  return frame_tree_node_->parent()->current_frame_host();
+}
+
 const base::TimeTicks& NavigationHandleImpl::NavigationStart() {
   return navigation_start_;
 }