Ignore show messages from RemoteFrames when the WebContents is hidden.

content/browser/renderer_host/render_widget_host_delegate.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "build/build_config.h"
 #include "content/browser/renderer_host/render_widget_host_delegate.h"
 #include "ui/gfx/geometry/rect.h"
 
 namespace content {
 
@@ skipping 53 matching lines @@
 
 bool RenderWidgetHostDelegate::HasMouseLock(
     RenderWidgetHostImpl* render_widget_host) {
   return false;
 }
 
 TextInputManager* RenderWidgetHostDelegate::GetTextInputManager() {
   return nullptr;
 }
 
+bool RenderWidgetHostDelegate::IsHidden() {
+  return false;
+}
+
 }  // namespace content