Use JavaObjectWeakGlobalRef in ContentViewCore.

content/browser/android/content_view_core_impl.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_BROWSER_ANDROID_CONTENT_VIEW_CORE_IMPL_H_
 #define CONTENT_BROWSER_ANDROID_CONTENT_VIEW_CORE_IMPL_H_
 
 #include <vector>
 
 #include "base/android/jni_helper.h"
@@ skipping 177 matching lines @@
 
   void SendGestureEvent(WebKit::WebInputEvent::Type type, long time_ms,
                         int x, int y,
                         float dx, float dy, bool link_preview_tap);
 
   void PostLoadUrl(const GURL& url);
 
   struct JavaObject;
   JavaObject* java_object_;
 
+  // A weak reference to the Java ContentViewCore object.
+  JavaObjectWeakGlobalRef java_ref_;
+
   NotificationRegistrar notification_registrar_;
 
   // Reference to the current WebContents used to determine how and what to
   // display in the ContentViewCore.
   WebContentsImpl* web_contents_;
 
   // We only set this to be the delegate of the web_contents if we own it.
   scoped_ptr<ContentViewClient> content_view_client_;
 
   // Whether the renderer backing this ContentViewCore has crashed.
   bool tab_crashed_;
 
   DISALLOW_COPY_AND_ASSIGN(ContentViewCoreImpl);
 };
 
 bool RegisterContentViewCore(JNIEnv* env);
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_ANDROID_CONTENT_VIEW_CORE_IMPL_H_