Fire visibilityChange event on out-of-process iframes.

extensions/renderer/scoped_web_frame.cc

 // Copyright 2015 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 "extensions/renderer/scoped_web_frame.h"
 
 #include "third_party/WebKit/public/web/WebHeap.h"
 
 namespace extensions {
 
 ScopedWebFrame::ScopedWebFrame() : view_(nullptr), frame_(nullptr) {
-  view_ = blink::WebView::create(nullptr);
+  view_ = blink::WebView::create(nullptr, true);
   frame_ = blink::WebLocalFrame::create(
       blink::WebTreeScopeType::Document, nullptr);
   view_->setMainFrame(frame_);
 }
 
 ScopedWebFrame::~ScopedWebFrame() {
   view_->close();
   frame_->close();
   blink::WebHeap::collectAllGarbageForTesting();
 }
 
 }  // namespace extensions