pass cachedLayout and cachedMeasure measures to plugin

Summary: Passing whether layout cache or measure cache was used or not

Reviewed By: davidaurelio

Differential Revision: D15920937

fbshipit-source-id: a6728e7af07ea228a285f824fbdfddc8130c5990

yoga/Yoga.cpp

@@ -3928,7 +3928,16 @@ bool YGLayoutNodeInternal(
   layout->generationCount = gCurrentGenerationCount;
 
 #ifdef YG_ENABLE_EVENTS
-  Event::publish<Event::NodeLayout>(node, {performLayout, layoutContext});
+  LayoutType layoutType;
+  if (performLayout) {
+    layoutType = !needToVisitNode && cachedResults == &layout->cachedLayout
+        ? LayoutType::kCachedLayout
+        : LayoutType::kLayout;
+  } else {
+    layoutType = cachedResults != nullptr ? LayoutType::kCachedMeasure
+                                          : LayoutType::kMeasure;
+  }
+  Event::publish<Event::NodeLayout>(node, {layoutType, layoutContext});
 #endif
 
   return (needToVisitNode || cachedResults == nullptr);

yoga/event/event.h

@@ -17,6 +17,13 @@ struct YGNode;
 namespace facebook {
 namespace yoga {
 
+enum LayoutType : int {
+  kLayout = 0,
+  kMeasure = 1,
+  kCachedLayout = 2,
+  kCachedMeasure = 3
+};
+
 struct Event {
   enum Type {
     NodeAllocation,
@@ -99,7 +106,7 @@ struct Event::TypedData<Event::NodeMeasure> {
 
 template <>
 struct Event::TypedData<Event::NodeLayout> {
-  bool performLayout;
+  LayoutType layoutType;
   void* layoutContext;
 };