Add FileSystemMountPointProvider::CreateFileReader() which returns appropriate Reader instance

webkit/fileapi/file_system_url_request_job.h

Index: webkit/fileapi/file_system_url_request_job.h
diff --git a/webkit/fileapi/file_system_url_request_job.h b/webkit/fileapi/file_system_url_request_job.h
index 9541c3160fa06892a6250bef11873e82eb5639e8..13391d7019eb6334b50d1d9a77fb175766bffa3a 100644
--- a/webkit/fileapi/file_system_url_request_job.h
+++ b/webkit/fileapi/file_system_url_request_job.h
@@ -19,9 +19,12 @@
 class GURL;
 class FilePath;
 
+namespace webkit_blob {
+class FileReader;
+}
+
 namespace fileapi {
 class FileSystemContext;
-class FileSystemFileReader;
 
 // A request job that handles reading filesystem: URLs
 class FileSystemURLRequestJob : public net::URLRequestJob {
@@ -63,7 +66,7 @@ class FileSystemURLRequestJob : public net::URLRequestJob {
   FileSystemContext* file_system_context_;
   scoped_refptr<base::MessageLoopProxy> file_thread_proxy_;
   base::WeakPtrFactory<FileSystemURLRequestJob> weak_factory_;
-  scoped_ptr<FileSystemFileReader> reader_;
+  scoped_ptr<webkit_blob::FileReader> reader_;
   bool is_directory_;
   scoped_ptr<net::HttpResponseInfo> response_info_;
   int64 remaining_bytes_;