Splitting DidSwap in cc::SwapPromise into WillSwap and DidSwap

cc/output/latency_info_swap_promise.cc

Index: cc/output/latency_info_swap_promise.cc
diff --git a/cc/output/latency_info_swap_promise.cc b/cc/output/latency_info_swap_promise.cc
index 96e08fc3436e8e3c27e4a5cccab6e06f744df4af..8cf78cb4caf6ce9eedd66be185e3f637e3b651b7 100644
--- a/cc/output/latency_info_swap_promise.cc
+++ b/cc/output/latency_info_swap_promise.cc
@@ -35,11 +35,13 @@ LatencyInfoSwapPromise::LatencyInfoSwapPromise(const ui::LatencyInfo& latency)
 LatencyInfoSwapPromise::~LatencyInfoSwapPromise() {
 }
 
-void LatencyInfoSwapPromise::DidSwap(CompositorFrameMetadata* metadata) {
+void LatencyInfoSwapPromise::WillSwap(CompositorFrameMetadata* metadata) {
   DCHECK(!latency_.terminated());
   metadata->latency_info.push_back(latency_);
 }
 
+void LatencyInfoSwapPromise::DidSwap() {}
+
 SwapPromise::DidNotSwapAction LatencyInfoSwapPromise::DidNotSwap(
     DidNotSwapReason reason) {
   latency_.AddLatencyNumber(DidNotSwapReasonToLatencyComponentType(reason), 0,