cc: Move OnScrollOffsetAnimated to scroll tree

cc/trees/layer_tree_host_unittest_animation.cc

Index: cc/trees/layer_tree_host_unittest_animation.cc
diff --git a/cc/trees/layer_tree_host_unittest_animation.cc b/cc/trees/layer_tree_host_unittest_animation.cc
index 0924115de364550433bd0cb925e67be29a7f3725..b32fdf7f20880298fae411fe2c4c1706c5014b32 100644
--- a/cc/trees/layer_tree_host_unittest_animation.cc
+++ b/cc/trees/layer_tree_host_unittest_animation.cc
@@ -772,6 +772,7 @@ class LayerTreeHostAnimationTestScrollOffsetAnimationTakeover
     scroll_layer_->SetBounds(gfx::Size(10000, 10000));
     client_.set_bounds(scroll_layer_->bounds());
     scroll_layer_->SetScrollOffset(gfx::ScrollOffset(10, 20));
+    scroll_layer_->SetScrollClipLayerId(layer_tree()->root_layer()->id());
     layer_tree()->root_layer()->AddChild(scroll_layer_);
 
     AttachPlayersToTimeline();
@@ -835,6 +836,7 @@ class LayerTreeHostAnimationTestScrollOffsetAnimationAdjusted
     scroll_layer_->SetBounds(gfx::Size(10000, 10000));
     client_.set_bounds(scroll_layer_->bounds());
     scroll_layer_->SetScrollOffset(gfx::ScrollOffset(10, 20));
+    scroll_layer_->SetScrollClipLayerId(layer_tree()->root_layer()->id());
     layer_tree()->root_layer()->AddChild(scroll_layer_);
 
     AttachPlayersToTimeline();