Change ppapi C++ comment style into C.

ppapi/c/dev/ppb_directory_reader_dev.h

Index: ppapi/c/dev/ppb_directory_reader_dev.h
diff --git a/ppapi/c/dev/ppb_directory_reader_dev.h b/ppapi/c/dev/ppb_directory_reader_dev.h
index 74a92ef86072d04e235ce17ef8db680a25e453fe..21c98249338f0114174f00d2f6c45431526eef0b 100644
--- a/ppapi/c/dev/ppb_directory_reader_dev.h
+++ b/ppapi/c/dev/ppb_directory_reader_dev.h
@@ -1,7 +1,7 @@
-// Copyright (c) 2010 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
+/* Copyright (c) 2010 The Chromium Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
 #ifndef PPAPI_C_DEV_PPB_DIRECTORY_READER_DEV_H_
 #define PPAPI_C_DEV_PPB_DIRECTORY_READER_DEV_H_
 
@@ -54,4 +54,5 @@ struct PPB_DirectoryReader_Dev {
                           struct PP_CompletionCallback callback);
 };
 
-#endif  // PPAPI_C_DEV_PPB_DIRECTORY_READER_DEV_H_
+#endif  /* PPAPI_C_DEV_PPB_DIRECTORY_READER_DEV_H_ */
+