Add SwapPromise support to LayerTreeHost and LayerTreeImpl

cc/trees/layer_tree_impl.h

Index: cc/trees/layer_tree_impl.h
diff --git a/cc/trees/layer_tree_impl.h b/cc/trees/layer_tree_impl.h
index 1b40b926faaa6a2c37a9e7f1ca00f213b9891499..9ff9efbd07c3b26575b969a11af540b74ad150a3 100644
--- a/cc/trees/layer_tree_impl.h
+++ b/cc/trees/layer_tree_impl.h
@@ -11,6 +11,7 @@
 
 #include "base/containers/hash_tables.h"
 #include "base/values.h"
+#include "cc/base/swap_promise.h"
 #include "cc/layers/layer_impl.h"
 #include "cc/resources/ui_resource_client.h"
 #include "ui/events/latency_info.h"
@@ -207,6 +208,17 @@ class CC_EXPORT LayerTreeImpl {
   const ui::LatencyInfo& GetLatencyInfo();
   void ClearLatencyInfo();
 
+  // Call this function when you expect there to be a swap buffer and want to
+  // have something done when the swap buffer actaully happens. Provide a
+  // did_swap_callback in the SwapPromise to be called when swap buffer happens,
+  // and a swap_aborted_callback to be called when the swap buffer is aborted (
+  // e.g. the next frame generated does not have actual damage).
+  void QueueSwapPromise(const SwapPromise& swap_promise);
+
+  void TakeSwapPromise(std::vector<SwapPromise>* new_swap_promise);
+  void FinishSwapPromise();
+  void BreakSwapPromise(const std::string& msg);
+
   void DidModifyTilePriorities();
 
   ResourceProvider::ResourceId ResourceIdForUIResource(UIResourceId uid) const;
@@ -269,6 +281,8 @@ class CC_EXPORT LayerTreeImpl {
 
   ui::LatencyInfo latency_info_;
 
+  std::vector<SwapPromise> swap_promise_list_;
+
   UIResourceRequestQueue ui_resource_request_queue_;
 
  private: