Make MediaFileUtil run on thread pool.

webkit/fileapi/file_system_operation_context.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 WEBKIT_FILEAPI_FILE_SYSTEM_OPERATION_CONTEXT_H_
 #define WEBKIT_FILEAPI_FILE_SYSTEM_OPERATION_CONTEXT_H_
 
 #include "base/logging.h"
 #include "base/memory/ref_counted.h"
+#include "base/sequenced_task_runner.h"
 #include "googleurl/src/gurl.h"
 #include "webkit/fileapi/fileapi_export.h"
 #include "webkit/fileapi/file_system_context.h"
 #include "webkit/fileapi/file_system_file_util.h"
 #include "webkit/fileapi/file_system_types.h"
 #include "webkit/fileapi/media/media_file_system_config.h"
 
 #if defined(SUPPORT_MEDIA_FILESYSTEM)
 #include "webkit/fileapi/media/media_device_interface_impl.h"
 #endif
 
-namespace base {
-class SequencedTaskRunner;
-}
-
 namespace fileapi {
 
 class MediaPathFilter;
 
 class FILEAPI_EXPORT_PRIVATE FileSystemOperationContext {
  public:
   explicit FileSystemOperationContext(FileSystemContext* context);
   ~FileSystemOperationContext();
 
   FileSystemContext* file_system_context() const {
     return file_system_context_.get();
   }
 
   void set_allowed_bytes_growth(const int64& allowed_bytes_growth) {
     allowed_bytes_growth_ = allowed_bytes_growth;
   }
   int64 allowed_bytes_growth() const { return allowed_bytes_growth_; }
 
 #if defined(SUPPORT_MEDIA_FILESYSTEM)
   void set_media_device(MediaDeviceInterfaceImpl* media_device) {
     media_device_ = media_device;
   }
 
   MediaDeviceInterfaceImpl* media_device() const {
     return media_device_.get();
   }
 #endif
 
-  base::SequencedTaskRunner* file_task_runner() const;
+  // Returns TaskRunner which the operation is performed on.
+  base::SequencedTaskRunner* task_runner() const {
+    return task_runner_.get();
+  }
+
+  // Overrides TaskRunner which the operation is performed on.
+  // file_system_context_->task_runners()->file_task_runner() is used otherwise.
+  void set_task_runner(base::SequencedTaskRunner* task_runner);
 
   void set_media_path_filter(MediaPathFilter* media_path_filter) {
     media_path_filter_ = media_path_filter;
   }
 
   MediaPathFilter* media_path_filter() {
     return media_path_filter_;
   }
 
  private:
   scoped_refptr<FileSystemContext> file_system_context_;
+  scoped_refptr<base::SequencedTaskRunner> task_runner_;
 
   int64 allowed_bytes_growth_;
   MediaPathFilter* media_path_filter_;
 
 #if defined(SUPPORT_MEDIA_FILESYSTEM)
   // Store the current media device.
   scoped_refptr<MediaDeviceInterfaceImpl> media_device_;
 #endif
 };
 
 }  // namespace fileapi
 
 #endif  // WEBKIT_FILEAPI_FILE_SYSTEM_OPERATION_CONTEXT_H_