Use JavaObjectWeakGlobalRef in ContentViewCore.

content/browser/android/download_controller.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.
 
 // This class pairs with DownloadController on Java side to forward requests
 // for GET downloads to the current DownloadListener. POST downloads are
 // handled on the native side.
 //
 // Both classes are Singleton classes. C++ object owns Java object.
 //
 // Call sequence
 // GET downloads:
 // DownloadController::NewGetDownload() =>
 // DownloadController.newHttpGetDownload() =>
 // DownloadListener.onDownloadStart() /
 // DownloadListener2.requestHttpGetDownload()
 //
 
 #ifndef CONTENT_BROWSER_ANDROID_DOWNLOAD_CONTROLLER_H_
 #define CONTENT_BROWSER_ANDROID_DOWNLOAD_CONTROLLER_H_
 
 #include <string>
 
 #include "base/android/jni_helper.h"
+#include "base/android/scoped_java_ref.h"
 #include "base/memory/singleton.h"
 #include "content/public/browser/download_item.h"
 #include "googleurl/src/gurl.h"
 #include "net/cookies/cookie_monster.h"
 
 namespace net {
 class URLRequest;
 }
 
 namespace content {
@@ skipping 67 matching lines @@
 
   void OnCookieResponse(DownloadInfoAndroid info,
                         int render_process_id,
                         int render_view_id,
                         const std::string& cookie);
 
   void StartAndroidDownload(const DownloadInfoAndroid& info,
                             int render_process_id,
                             int render_view_id);
 
-  jobject GetContentViewCoreFromWebContents(WebContents* web_contents);
-  jobject GetContentView(int render_process_id, int render_view_id);
+  base::android::ScopedJavaLocalRef<jobject> GetContentViewCoreFromWebContents(
+      WebContents* web_contents);
+
+  base::android::ScopedJavaLocalRef<jobject> GetContentView(
+      int render_process_id, int render_view_id);
 
   // Creates Java object if it is not created already and returns it.
   JavaObject* GetJavaObject();
 
   JavaObject* java_object_;
 
   DISALLOW_COPY_AND_ASSIGN(DownloadController);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_ANDROID_DOWNLOAD_CONTROLLER_H_