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

webkit/fileapi/sandbox_mount_point_provider.cc

Index: webkit/fileapi/sandbox_mount_point_provider.cc
diff --git a/webkit/fileapi/sandbox_mount_point_provider.cc b/webkit/fileapi/sandbox_mount_point_provider.cc
index 138629c9defe72395d8c4822365369c41a684416..2abed566864d48c4307bc9ecb2e6e90f00c28856 100644
--- a/webkit/fileapi/sandbox_mount_point_provider.cc
+++ b/webkit/fileapi/sandbox_mount_point_provider.cc
@@ -16,6 +16,7 @@
 #include "base/metrics/histogram.h"
 #include "googleurl/src/gurl.h"
 #include "net/base/net_util.h"
+#include "webkit/fileapi/file_system_file_reader.h"
 #include "webkit/fileapi/file_system_operation.h"
 #include "webkit/fileapi/file_system_operation_context.h"
 #include "webkit/fileapi/file_system_options.h"
@@ -433,6 +434,14 @@ SandboxMountPointProvider::CreateFileSystemOperation(
   return new FileSystemOperation(file_proxy, context);
 }
 
+webkit_blob::FileReader* SandboxMountPointProvider::CreateFileReader(
+    const GURL& url,
+    int64 offset,
+    base::MessageLoopProxy* file_proxy,
+    FileSystemContext* context) const {
+  return new FileSystemFileReader(file_proxy, context, url, offset);
+}
+
 FilePath SandboxMountPointProvider::old_base_path() const {
   return profile_path_.Append(kOldFileSystemDirectory);
 }