Fix the WebStrings leak in MockWebClipboardImpl

content/test/mock_webclipboard_impl.h

 // Copyright 2013 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.
 //
 // This file mocks out just enough of the WebClipboard API for running the
 // webkit tests. This is so we can run webkit tests without them sharing a
 // clipboard, which allows for running them in parallel and having the tests
 // not interact with actual user actions.
 
 #ifndef CONTENT_TEST_MOCK_WEBCLIPBOARD_IMPL_H_
 #define CONTENT_TEST_MOCK_WEBCLIPBOARD_IMPL_H_
 
 #include <map>
+#include <string>
 
 #include "base/strings/string16.h"
 #include "third_party/WebKit/public/platform/WebClipboard.h"
 #include "third_party/WebKit/public/platform/WebDragData.h"
 #include "third_party/WebKit/public/platform/WebImage.h"
 
 namespace content {
 
 class MockWebClipboardImpl : public blink::WebClipboard {
  public:
@@ skipping 21 matching lines @@
   virtual void writeURL(
       const blink::WebURL& url, const blink::WebString& title);
   virtual void writeImage(
       const blink::WebImage& image, const blink::WebURL& url,
       const blink::WebString& title);
   virtual void writeDataObject(const blink::WebDragData& data);
 
  private:
   void clear();
 
-  blink::WebString m_plainText;
-  blink::WebString m_htmlText;
+  std::string m_plainText;
+  std::string m_htmlText;
   blink::WebImage m_image;
   std::map<base::string16, base::string16> m_customData;
   bool m_writeSmartPaste;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_TEST_MOCK_WEBCLIPBOARD_IMPL_H_