Make document.activeElement work with OOPIF

content/browser/frame_host/frame_tree.cc

Index: content/browser/frame_host/frame_tree.cc
diff --git a/content/browser/frame_host/frame_tree.cc b/content/browser/frame_host/frame_tree.cc
index cddea8333fd214ee43851fa0ee1f71b77b8d8bae..5c70f34f6c94c9394902b392238841d413a77b3a 100644
--- a/content/browser/frame_host/frame_tree.cc
+++ b/content/browser/frame_host/frame_tree.cc
@@ -271,12 +271,16 @@ void FrameTree::SetFocusedFrame(FrameTreeNode* node) {
   // If the focused frame changed across processes, send a message to the old
   // focused frame's renderer process to clear focus from that frame and fire
   // blur events.
-  FrameTreeNode* oldFocusedFrame = GetFocusedFrame();
-  if (oldFocusedFrame &&
-      oldFocusedFrame->current_frame_host()->GetSiteInstance() !=
-          node->current_frame_host()->GetSiteInstance()) {
-    DCHECK(SiteIsolationPolicy::AreCrossProcessFramesPossible());
-    oldFocusedFrame->current_frame_host()->ClearFocus();
+  FrameTreeNode* old_focused_frame = GetFocusedFrame();
+  if (old_focused_frame) {
+    SiteInstance* old_site_instance =
+        old_focused_frame->current_frame_host()->GetSiteInstance();
+    if (old_site_instance != node->current_frame_host()->GetSiteInstance()) {
+      DCHECK(SiteIsolationPolicy::AreCrossProcessFramesPossible());
+      RenderFrameProxyHost* proxy =
+          node->render_manager()->GetRenderFrameProxyHost(old_site_instance);
+      proxy->SetFocusedFrame();
+    }
   }
 
   node->set_last_focus_time(base::TimeTicks::Now());