LatencyInfo trace_id_ no longer dependent on sequence_number.

cc/trees/layer_tree_host_impl_unittest.cc

Index: cc/trees/layer_tree_host_impl_unittest.cc
diff --git a/cc/trees/layer_tree_host_impl_unittest.cc b/cc/trees/layer_tree_host_impl_unittest.cc
index ab3e801b5238ecbc5dfb0209298b57a512582b6d..f37061a62e7cdc0ce7aad874b13812859bf25cff 100644
--- a/cc/trees/layer_tree_host_impl_unittest.cc
+++ b/cc/trees/layer_tree_host_impl_unittest.cc
@@ -2129,6 +2129,7 @@ TEST_F(LayerTreeHostImplTest, ImplPinchZoomWheelBubbleBetweenViewports) {
 
 TEST_F(LayerTreeHostImplTest, ScrollWithSwapPromises) {
   ui::LatencyInfo latency_info;
+  latency_info.set_trace_id(5);
   latency_info.AddLatencyNumber(ui::INPUT_EVENT_LATENCY_BEGIN_RWH_COMPONENT, 0,
                                 1234);
   std::unique_ptr<SwapPromise> swap_promise(
@@ -9242,6 +9243,7 @@ TEST_F(LayerTreeHostImplTest, LatencyInfoPassedToCompositorFrameMetadata) {
       static_cast<FakeLayerTreeFrameSink*>(host_impl_->layer_tree_frame_sink());
 
   ui::LatencyInfo latency_info;
+  latency_info.set_trace_id(5);
   latency_info.AddLatencyNumber(ui::INPUT_EVENT_LATENCY_BEGIN_RWH_COMPONENT, 0,
                                 0);
   std::unique_ptr<SwapPromise> swap_promise(