Fix accessibility with out-of-process iframes.

content/public/test/browser_test_utils.h

 // 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.
 
 #ifndef CONTENT_PUBLIC_TEST_BROWSER_TEST_UTILS_H_
 #define CONTENT_PUBLIC_TEST_BROWSER_TEST_UTILS_H_
 
 #include <queue>
 #include <string>
 #include <vector>
@@ skipping 416 matching lines @@
   bool OnMessageReceived(const IPC::Message& message) override;
 
   void ReceivedFrameSwap();
 
   int frames_to_wait_;
   base::Closure quit_;
 
   DISALLOW_COPY_AND_ASSIGN(FrameWatcher);
 };
 
+// This observer keeps track of the last deleted RenderFrame to avoid
+// accessing it and causing use-after-free condition.
+class RenderFrameDeletedObserver : public WebContentsObserver {
+ public:
+  RenderFrameDeletedObserver(RenderFrameHost* rfh);
+  ~RenderFrameDeletedObserver() override;
+  void RenderFrameDeleted(RenderFrameHost* render_frame_host) override;
+  bool deleted();
+  void WaitUntilDeleted();
+
+ private:
+  int process_id_;
+  int routing_id_;
+  bool deleted_;
+  scoped_ptr<base::RunLoop> runner_;
+
+  DISALLOW_COPY_AND_ASSIGN(RenderFrameDeletedObserver);
+};
+
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_TEST_BROWSER_TEST_UTILS_H_