Fixed rounding issue on scrollbar rasterization.

cc/test/fake_painted_scrollbar_layer.h

Index: cc/test/fake_painted_scrollbar_layer.h
diff --git a/cc/test/fake_painted_scrollbar_layer.h b/cc/test/fake_painted_scrollbar_layer.h
index 9b1b13dab2cc555f2a79768670226a7ed5eb7015..1e0cba7ad5bf7555094fad524b845e361ff1639a 100644
--- a/cc/test/fake_painted_scrollbar_layer.h
+++ b/cc/test/fake_painted_scrollbar_layer.h
@@ -16,7 +16,15 @@ namespace cc {
 class FakePaintedScrollbarLayer : public PaintedScrollbarLayer {
  public:
   static scoped_refptr<FakePaintedScrollbarLayer>
-      Create(bool paint_during_update, bool has_thumb, int scrolling_layer_id);
+      Create(bool paint_during_update,
+             bool has_thumb,
+             int scrolling_layer_id);
+  static scoped_refptr<FakePaintedScrollbarLayer>
+      Create(bool paint_during_update,
+             bool has_thumb,
+             int scrolling_layer_id,
+             FakeScrollbar* fake_scrollbar);
+
   int update_count() const { return update_count_; }
   void reset_update_count() { update_count_ = 0; }