Change ppapi C++ comment style into C.

ppapi/c/dev/ppb_font_dev.h

Index: ppapi/c/dev/ppb_font_dev.h
diff --git a/ppapi/c/dev/ppb_font_dev.h b/ppapi/c/dev/ppb_font_dev.h
index 747cb7c2d173db50cb9e55113fc71af1c9446406..226285601ff09015fd0c0b4dcaf64c805e9f79cb 100644
--- a/ppapi/c/dev/ppb_font_dev.h
+++ b/ppapi/c/dev/ppb_font_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_FONT_DEV_H_
 #define PPAPI_C_DEV_PPB_FONT_DEV_H_
 
@@ -173,4 +173,5 @@ struct PPB_Font_Dev {
                                      uint32_t char_offset);
 };
 
-#endif  // PPAPI_C_DEV_PPB_FONT_DEV_H_
+#endif  /* PPAPI_C_DEV_PPB_FONT_DEV_H_ */
+