chromeos: Destruct DriveResourceMetadata on the blocking pool

chrome/browser/chromeos/drive/drive_resource_metadata.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 CHROME_BROWSER_CHROMEOS_DRIVE_DRIVE_RESOURCE_METADATA_H_
 #define CHROME_BROWSER_CHROMEOS_DRIVE_DRIVE_RESOURCE_METADATA_H_
 
 #include <map>
 #include <set>
 #include <string>
@@ skipping 119 matching lines @@
 typedef base::Callback<void(scoped_ptr<EntryInfoPairResult> pair_result)>
     GetEntryInfoPairCallback;
 
 // Storage for Drive Metadata.
 class DriveResourceMetadata {
  public:
   // |root_resource_id| is the resource id for the root directory.
   DriveResourceMetadata(
       const std::string& root_resource_id,
       scoped_refptr<base::SequencedTaskRunner> blocking_task_runner);
-  virtual ~DriveResourceMetadata();
+
+  // Destroys this object.  This method posts a task to |blocking_task_runner_|
+  // to safely delete this object.
+  void Destroy();
 
   // True if the file system feed is loaded from the cache or from the server.
   bool loaded() const { return loaded_; }
   void set_loaded(bool loaded) { loaded_ = loaded; }
 
   // Largest change timestamp that was the source of content for the current
   // state of the root directory.
   void GetLargestChangestamp(const GetChangestampCallback& callback);
   void SetLargestChangestamp(int64 value,
                              const FileOperationCallback& callback);
@@ skipping 76 matching lines @@
   // Saves metadata to the specified directory when appropriate.
   void MaybeSave(const base::FilePath& directory_path);
 
   // Loads metadata from the specified directory.
   void Load(const base::FilePath& directory_path,
             const FileOperationCallback& callback);
 
  private:
   friend class DriveResourceMetadataTest;
 
+  // Note: Use Destroy() to delete this object.
+  virtual ~DriveResourceMetadata();
+
+  // Used to implement Destroy().
+  void DestroyOnBlockingPool();
+
   // Clears root_ and the resource map.
   void ClearRoot();
 
   // Continues with GetEntryInfoPairByPaths after the first DriveEntry has been
   // asynchronously fetched. This fetches the second DriveEntry only if the
   // first was found.
   void GetEntryInfoPairByPathsAfterGetFirst(
       const base::FilePath& first_path,
       const base::FilePath& second_path,
       const GetEntryInfoPairCallback& callback,
@@ skipping 75 matching lines @@
   // This should remain the last member so it'll be destroyed first and
   // invalidate its weak pointers before other members are destroyed.
   base::WeakPtrFactory<DriveResourceMetadata> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(DriveResourceMetadata);
 };
 
 }  // namespace drive
 
 #endif  // CHROME_BROWSER_CHROMEOS_DRIVE_DRIVE_RESOURCE_METADATA_H_