Change ppapi C++ comment style into C.

ppapi/c/dev/ppb_scrollbar_dev.h

Index: ppapi/c/dev/ppb_scrollbar_dev.h
diff --git a/ppapi/c/dev/ppb_scrollbar_dev.h b/ppapi/c/dev/ppb_scrollbar_dev.h
index 4166840263252ac42f8ccd749ef92319f067cc4e..6df768366343dde6113aaca3d24f57d6ed8bff35 100644
--- a/ppapi/c/dev/ppb_scrollbar_dev.h
+++ b/ppapi/c/dev/ppb_scrollbar_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_SCROLLBAR_DEV_H_
 #define PPAPI_C_DEV_PPB_SCROLLBAR_DEV_H_
 
@@ -62,4 +62,5 @@ struct PPB_Scrollbar_Dev {
                    int32_t multiplier);
 };
 
-#endif  // PPAPI_C_DEV_PPB_SCROLLBAR_DEV_H_
+#endif  /* PPAPI_C_DEV_PPB_SCROLLBAR_DEV_H_ */
+