Remove some LatencyInfo merging code path

cc/base/latency_info_swap_promise.cc

Index: cc/base/latency_info_swap_promise.cc
diff --git a/cc/base/latency_info_swap_promise.cc b/cc/base/latency_info_swap_promise.cc
index 41c0e997d1176fffd55d9d8f62cae478b2b74595..cc2f1c10292e6b935fad034219efcff47a573fcb 100644
--- a/cc/base/latency_info_swap_promise.cc
+++ b/cc/base/latency_info_swap_promise.cc
@@ -34,9 +34,7 @@ LatencyInfoSwapPromise::~LatencyInfoSwapPromise() {
 
 void LatencyInfoSwapPromise::DidSwap(CompositorFrameMetadata* metadata) {
   DCHECK(!latency_.terminated);
-  // TODO(miletus): Append the |latency_| into metadata's LatencyInfo list
-  // once we remove LatencyInfo merge in GPU side.
-  metadata->latency_info.MergeWith(latency_);
+  metadata->latency_info.push_back(latency_);
 }
 
 void LatencyInfoSwapPromise::DidNotSwap(DidNotSwapReason reason) {