Round the scroll offset synced back to main instead of flooring.

cc/trees/layer_tree_host_unittest_scroll.cc

Index: cc/trees/layer_tree_host_unittest_scroll.cc
diff --git a/cc/trees/layer_tree_host_unittest_scroll.cc b/cc/trees/layer_tree_host_unittest_scroll.cc
index 248877ffe82b09e665b3cfc401af02a44ce93695..a34b38d6ea6d214b68eeeb247066b79311e73e7e 100644
--- a/cc/trees/layer_tree_host_unittest_scroll.cc
+++ b/cc/trees/layer_tree_host_unittest_scroll.cc
@@ -462,20 +462,22 @@ class LayerTreeHostScrollTestFractionalScroll : public LayerTreeHostScrollTest {
         break;
       case 1:
         EXPECT_VECTOR_EQ(
-            gfx::ToFlooredVector2d(scroll_amount_),
+            gfx::ToRoundedVector2d(scroll_amount_),
             ScrollTreeForLayer(scroll_layer)
                 ->GetScrollOffsetBaseForTesting(scroll_layer->id()));
-        EXPECT_VECTOR_EQ(gfx::Vector2dF(fmod(scroll_amount_.x(), 1.0f), 0.0f),
-                         ScrollDelta(scroll_layer));
+        EXPECT_VECTOR_EQ(
+            scroll_amount_ - gfx::ToRoundedVector2d(scroll_amount_),
+            ScrollDelta(scroll_layer));
         PostSetNeedsCommitToMainThread();
         break;
       case 2:
         EXPECT_VECTOR_EQ(
-            gfx::ToFlooredVector2d(scroll_amount_ + scroll_amount_),
+            gfx::ToRoundedVector2d(scroll_amount_ + scroll_amount_),
             ScrollTreeForLayer(scroll_layer)
                 ->GetScrollOffsetBaseForTesting(scroll_layer->id()));
         EXPECT_VECTOR_EQ(
-            gfx::Vector2dF(fmod(2.0f * scroll_amount_.x(), 1.0f), 0.0f),
+            scroll_amount_ + scroll_amount_ -
+                gfx::ToRoundedVector2d(scroll_amount_ + scroll_amount_),
             ScrollDelta(scroll_layer));
         EndTest();
         break;