mediaview: Implement ArcDocumentsProviderBackendDelegate.

chrome/browser/chromeos/arc/fileapi/arc_documents_provider_backend_delegate.h

 // Copyright 2016 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 CHROME_BROWSER_CHROMEOS_ARC_FILEAPI_ARC_DOCUMENTS_PROVIDER_BACKEND_DELEGATE_H_
 #define CHROME_BROWSER_CHROMEOS_ARC_FILEAPI_ARC_DOCUMENTS_PROVIDER_BACKEND_DELEGATE_H_
 
 #include <memory>
 
 #include "base/macros.h"
+#include "base/memory/weak_ptr.h"
 #include "chrome/browser/chromeos/arc/fileapi/arc_documents_provider_async_file_util.h"
 #include "chrome/browser/chromeos/arc/fileapi/arc_documents_provider_root_map.h"
 #include "chrome/browser/chromeos/fileapi/file_system_backend_delegate.h"
 
 namespace arc {
 
 // Implements ARC documents provider filesystem.
 class ArcDocumentsProviderBackendDelegate
     : public chromeos::FileSystemBackendDelegate {
  public:
@@ skipping 14 matching lines @@
       int64_t offset,
       storage::FileSystemContext* context) override;
   storage::WatcherManager* GetWatcherManager(
       storage::FileSystemType type) override;
   void GetRedirectURLForContents(const storage::FileSystemURL& url,
                                  const storage::URLCallback& callback) override;
 
  private:
   ArcDocumentsProviderRootMap roots_;
   ArcDocumentsProviderAsyncFileUtil async_file_util_;
+  base::WeakPtrFactory<ArcDocumentsProviderBackendDelegate> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ArcDocumentsProviderBackendDelegate);
 };
 
 }  // namespace arc
 
 #endif  // CHROME_BROWSER_CHROMEOS_ARC_FILEAPI_ARC_DOCUMENTS_PROVIDER_BACKEND_DELEGATE_H_