Don't route a non-frame widget's keyboard event to main frame widget.

content/browser/web_contents/web_contents_impl.cc

Index: content/browser/web_contents/web_contents_impl.cc
diff --git a/content/browser/web_contents/web_contents_impl.cc b/content/browser/web_contents/web_contents_impl.cc
index bfae0c2414406717893f98f7a8df07f750eac9a3..9c23bb86eae1a6a2f4e96b8355c01f1ff6311112 100644
--- a/content/browser/web_contents/web_contents_impl.cc
+++ b/content/browser/web_contents/web_contents_impl.cc
@@ -1597,13 +1597,19 @@ void WebContentsImpl::ReplicatePageFocus(bool is_focused) {
   frame_tree_.ReplicatePageFocus(is_focused);
 }
 
-RenderWidgetHostImpl* WebContentsImpl::GetFocusedRenderWidgetHost() {
+RenderWidgetHostImpl* WebContentsImpl::GetFocusedRenderWidgetHost(
+    RenderWidgetHostImpl* receiving_widget) {
   if (!SiteIsolationPolicy::AreCrossProcessFramesPossible())
-    return GetMainFrame()->GetRenderWidgetHost();
+    return receiving_widget;
+
+  // Events for widgets other than the main frame (e.g., popup menus) should be
+  // forwarded directly to the widget they arrived on.
+  if (receiving_widget != GetMainFrame()->GetRenderWidgetHost())
+    return receiving_widget;
 
   FrameTreeNode* focused_frame = frame_tree_.GetFocusedFrame();
   if (!focused_frame)
-    return GetMainFrame()->GetRenderWidgetHost();
+    return receiving_widget;
 
   return RenderWidgetHostImpl::From(
       focused_frame->current_frame_host()->GetView()->GetRenderWidgetHost());