gfx: Make conversions from Size to SizeF be explicit.

cc/layers/picture_layer_impl_unittest.cc

Index: cc/layers/picture_layer_impl_unittest.cc
diff --git a/cc/layers/picture_layer_impl_unittest.cc b/cc/layers/picture_layer_impl_unittest.cc
index 1628c0c5c76f384b3554af4c6afd3f333ee047fb..e239c6ba2ab20f3b65104d262a47e83c9c866306 100644
--- a/cc/layers/picture_layer_impl_unittest.cc
+++ b/cc/layers/picture_layer_impl_unittest.cc
@@ -1562,7 +1562,7 @@ TEST_F(PictureLayerImplTest, ScaledMaskLayer) {
   active_mask->GetContentsResourceId(&mask_resource_id, &mask_texture_size);
   EXPECT_NE(0u, mask_resource_id);
   gfx::Size expected_mask_texture_size =
-      gfx::ToCeiledSize(gfx::ScaleSize(active_mask->bounds(), 1.3f));
+      gfx::ScaleToCeiledSize(active_mask->bounds(), 1.3f);
   EXPECT_EQ(mask_texture_size, expected_mask_texture_size);
 }