Make MediaFileUtil run on thread pool.

webkit/fileapi/file_system_file_stream_reader.cc

Index: webkit/fileapi/file_system_file_stream_reader.cc
diff --git a/webkit/fileapi/file_system_file_stream_reader.cc b/webkit/fileapi/file_system_file_stream_reader.cc
index f8e9afd41badc6ac4adbd4c37b2a916341361e0f..c5ee232067e47692a9ce847596ddb3887d1c7b1c 100644
--- a/webkit/fileapi/file_system_file_stream_reader.cc
+++ b/webkit/fileapi/file_system_file_stream_reader.cc
@@ -6,13 +6,14 @@
 
 #include "base/file_util_proxy.h"
 #include "base/platform_file.h"
-#include "base/sequenced_task_runner.h"
+#include "base/single_thread_task_runner.h"
 #include "net/base/file_stream.h"
 #include "net/base/io_buffer.h"
 #include "net/base/net_errors.h"
 #include "webkit/blob/local_file_stream_reader.h"
 #include "webkit/fileapi/file_system_context.h"
 #include "webkit/fileapi/file_system_operation_interface.h"
+#include "webkit/fileapi/file_system_task_runners.h"
 
 using webkit_blob::LocalFileStreamReader;
 
@@ -30,7 +31,7 @@ void ReadAdapter(base::WeakPtr<FileSystemFileStreamReader> reader,
     callback.Run(rv);
 }
 
-}
+}  // namespace
 
 FileSystemFileStreamReader::FileSystemFileStreamReader(
     FileSystemContext* file_system_context,
@@ -87,10 +88,9 @@ void FileSystemFileStreamReader::DidCreateSnapshot(
   snapshot_ref_ = file_ref;
 
   local_file_reader_.reset(
-      new LocalFileStreamReader(file_system_context_->file_task_runner(),
-                                platform_path,
-                                initial_offset_,
-                                base::Time()));
+      new LocalFileStreamReader(
+          file_system_context_->task_runners()->file_task_runner(),
+          platform_path, initial_offset_, base::Time()));
 
   read_closure.Run();
 }