Use swap-promise to improve first* paint times

third_party/WebKit/public/platform/WebLayerTreeView.h

Index: third_party/WebKit/public/platform/WebLayerTreeView.h
diff --git a/third_party/WebKit/public/platform/WebLayerTreeView.h b/third_party/WebKit/public/platform/WebLayerTreeView.h
index 35b27082dddb4fc3bc8fa7e55b632f92cdfa2d4f..a9fe23823883920e4feb6eb1f0176e01de8ea087 100644
--- a/third_party/WebKit/public/platform/WebLayerTreeView.h
+++ b/third_party/WebKit/public/platform/WebLayerTreeView.h
@@ -33,6 +33,7 @@
 #include "WebEventListenerProperties.h"
 #include "WebFloatPoint.h"
 #include "WebSize.h"
+#include "base/callback.h"
 #include "cc/surfaces/frame_sink_id.h"
 
 namespace cc {
@@ -181,6 +182,8 @@ class WebLayerTreeView {
 
   // Toggles scroll bottleneck rects on the HUD layer
   virtual void SetShowScrollBottleneckRects(bool) {}
+
+  virtual void NotifySwapTime(base::Callback<void(bool, double)> callback) {}
 };
 
 }  // namespace blink