base::Bind: Convert FileUtilProxy::EnsureFileExistsCallback.

BUG=none
TEST=none

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Review URL: http://codereview.chromium.org/8311012

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@105883 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/webkit/fileapi/file_system_file_util_proxy.h b/webkit/fileapi/file_system_file_util_proxy.h
index e05b81a..67d6c8b 100644
--- a/webkit/fileapi/file_system_file_util_proxy.h
+++ b/webkit/fileapi/file_system_file_util_proxy.h
@@ -75,7 +75,7 @@
       const FileSystemOperationContext& context,
       scoped_refptr<MessageLoopProxy> message_loop_proxy,
       const FilePath& file_path,
-      EnsureFileExistsCallback* callback);
+      const EnsureFileExistsCallback& callback);
 
   // Maps virtual file patch to its local physical location.
   static bool GetLocalPath(