Make MediaFileUtil run on thread pool.

webkit/fileapi/file_system_operation_context.h

Index: webkit/fileapi/file_system_operation_context.h
diff --git a/webkit/fileapi/file_system_operation_context.h b/webkit/fileapi/file_system_operation_context.h
index 3a8cc3931b0c2afbf6e3026b1a76d433ab554ac2..080e71ce2f6df886bae451c2c50ae6b28b28f037 100644
--- a/webkit/fileapi/file_system_operation_context.h
+++ b/webkit/fileapi/file_system_operation_context.h
@@ -50,7 +50,14 @@ class FILEAPI_EXPORT_PRIVATE FileSystemOperationContext {
   }
 #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 thread is set as default value.

[kinuko, 2012/08/03 23:13:39]

nit: "file_system_context_->task_runners()->file_task_runner() is used
otherwise."

This method is not inline but it's a still simplest setter so I'd feel this
should be named set_task_runner()... though not 100% sure.

[tzik, 2012/08/04 00:24:21]

Done.

+  void SetTaskRunner(base::SequencedTaskRunner* task_runner);
 
   void set_media_path_filter(MediaPathFilter* media_path_filter) {
     media_path_filter_ = media_path_filter;
@@ -62,6 +69,7 @@ class FILEAPI_EXPORT_PRIVATE FileSystemOperationContext {
 
  private:
   scoped_refptr<FileSystemContext> file_system_context_;
+  scoped_refptr<base::SequencedTaskRunner> task_runner_;
 
   int64 allowed_bytes_growth_;
   MediaPathFilter* media_path_filter_;