Code: void RenderViewImpl::DidFocus() {
  WebFrame* main_frame = webview() ? webview()->MainFrame() : nullptr;
  bool is_processing_user_gesture =
      WebUserGestureIndicator::IsProcessingUserGesture(
          main_frame && main_frame->IsWebLocalFrame()
              ? main_frame->ToWebLocalFrame()
              : nullptr);
   if (is_processing_user_gesture &&
       !RenderThreadImpl::current()->layout_test_mode()) {
     Send(new ViewHostMsg_Focus(GetRoutingID()));
   }
 }

Vulnerability Type: 
CWE ID: 
Summary: A JavaScript focused window could overlap the fullscreen notification in Fullscreen in Google Chrome prior to 66.0.3359.117 allowed a remote attacker to obscure the full screen warning via a crafted HTML page.
Commit Message: If a page calls |window.focus()|, kick it out of fullscreen.

BUG=776418, 800056

Change-Id: I1880fe600e4814c073f247c43b1c1ac80c8fc017
Reviewed-on: https://chromium-review.googlesource.com/852378
Reviewed-by: Nasko Oskov <nasko@chromium.org>
Reviewed-by: Philip Jägenstedt <foolip@chromium.org>
Commit-Queue: Avi Drissman <avi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#533790}