Track live instance and allocation counts for classes

runtime/vm/scavenger.h

Index: runtime/vm/scavenger.h
diff --git a/runtime/vm/scavenger.h b/runtime/vm/scavenger.h
index 249df65d00540c739006d01f4125b35a2fe9c8cd..83e8a57586e2123d0f3f3e2d65f4628aece4155e 100644
--- a/runtime/vm/scavenger.h
+++ b/runtime/vm/scavenger.h
@@ -18,6 +18,7 @@ namespace dart {
 // Forward declarations.
 class Heap;
 class Isolate;
+class JSONObject;
 class ScavengerVisitor;
 
 DECLARE_FLAG(bool, gc_at_alloc);
@@ -89,6 +90,24 @@ class Scavenger {
 
   void WriteProtect(bool read_only);
 
+  void AddGCTime(int64_t micros) {
+    gc_time_micros_ += micros;
+  }
+
+  int64_t gc_time_micros() const {
+    return gc_time_micros_;
+  }
+
+  void IncrementCollections() {
+    collections_++;
+  }
+
+  intptr_t collections() const {
+    return collections_;
+  }
+
+  void PrintToJSONObject(JSONObject* object);
+
  private:
   // Ids for time and data records in Heap::GCStats.
   enum {
@@ -172,6 +191,9 @@ class Scavenger {
   // Keep track whether the scavenge had a promotion failure.
   bool had_promotion_failure_;
 
+  int64_t gc_time_micros_;
+  intptr_t collections_;
+
   friend class ScavengerVisitor;
   friend class ScavengerWeakVisitor;