Change ppapi C++ comment style into C.

ppapi/c/dev/ppb_widget_dev.h

Index: ppapi/c/dev/ppb_widget_dev.h
diff --git a/ppapi/c/dev/ppb_widget_dev.h b/ppapi/c/dev/ppb_widget_dev.h
index 3d23e0ea7155a0d7cb320900bd8176711c8c7e7e..1c2edfdbf11d4a76a0090aab3389c6b391a3a7d9 100644
--- a/ppapi/c/dev/ppb_widget_dev.h
+++ b/ppapi/c/dev/ppb_widget_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_WIDGET_DEV_H_
 #define PPAPI_C_DEV_PPB_WIDGET_DEV_H_
 
@@ -38,4 +38,5 @@ struct PPB_Widget_Dev {
                       const struct PP_Rect* location);
 };
 
-#endif  // PPAPI_C_DEV_PPB_WIDGET_DEV_H_
+#endif  /* PPAPI_C_DEV_PPB_WIDGET_DEV_H_ */
+