Fix RFH::OnUpdateUserActivationState for deleted RFH case.

Bug: 780556
Change-Id: Ic1feadf01adc9ea60b9246c57e503b29e801e305
Reviewed-on: https://chromium-review.googlesource.com/1089117
Commit-Queue: Mustaq Ahmed <mustaq@chromium.org>
Reviewed-by: Alex Moshchuk <alexmos@chromium.org>
Cr-Commit-Position: refs/heads/master@{#565003}

content/browser/frame_host/render_frame_host_impl.cc

@@ -2847,6 +2847,8 @@ void RenderFrameHostImpl::NotifyUserActivation() {
 
 void RenderFrameHostImpl::OnUpdateUserActivationState(
     blink::UserActivationUpdateType update_type) {
+  if (!is_active())
+    return;
   frame_tree_node_->UpdateUserActivationState(update_type);
 }