Convert //cc from scoped_ptr to std::unique_ptr.

cc/blink/scrollbar_impl.cc

Index: cc/blink/scrollbar_impl.cc
diff --git a/cc/blink/scrollbar_impl.cc b/cc/blink/scrollbar_impl.cc
index 6f5fe31d12de71d09f44cd1c65eb37d5e1999fae..5df7cfe45ec67f474839eed124a7e5537ae131ab 100644
--- a/cc/blink/scrollbar_impl.cc
+++ b/cc/blink/scrollbar_impl.cc
@@ -13,9 +13,9 @@ using blink::WebScrollbar;
 namespace cc_blink {
 
 ScrollbarImpl::ScrollbarImpl(
-    scoped_ptr<WebScrollbar> scrollbar,
+    std::unique_ptr<WebScrollbar> scrollbar,
     blink::WebScrollbarThemePainter painter,
-    scoped_ptr<blink::WebScrollbarThemeGeometry> geometry)
+    std::unique_ptr<blink::WebScrollbarThemeGeometry> geometry)
     : scrollbar_(std::move(scrollbar)),
       painter_(painter),
       geometry_(std::move(geometry)) {}