Use LatencyInfoSwapPromise to track LatencyInfo through compositor

cc/trees/layer_tree_host.cc

Index: cc/trees/layer_tree_host.cc
diff --git a/cc/trees/layer_tree_host.cc b/cc/trees/layer_tree_host.cc
index ac471c395aea52fc303b0de0fa3d523e89421248..e26f1851499a41d06e95635cbd2f97cd08cb21b1 100644
--- a/cc/trees/layer_tree_host.cc
+++ b/cc/trees/layer_tree_host.cc
@@ -382,8 +382,6 @@ void LayerTreeHost::FinishCommitOnImplThread(LayerTreeHostImpl* host_impl) {
                                          min_page_scale_factor_,
                                          max_page_scale_factor_);
   sync_tree->SetPageScaleDelta(page_scale_delta / sent_page_scale_delta);
-  sync_tree->SetLatencyInfo(latency_info_);
-  latency_info_.Clear();
 
   sync_tree->PassSwapPromises(&swap_promise_list_);
 
@@ -705,10 +703,6 @@ void LayerTreeHost::SetVisible(bool visible) {
   proxy_->SetVisible(visible);
 }
 
-void LayerTreeHost::SetLatencyInfo(const ui::LatencyInfo& latency_info) {
-  latency_info_.MergeWith(latency_info);
-}
-
 void LayerTreeHost::StartPageScaleAnimation(gfx::Vector2d target_offset,
                                             bool use_anchor,
                                             float scale,