Explicitly track whether incremental marking was activated

src/heap/incremental-marking.h

Index: src/heap/incremental-marking.h
diff --git a/src/heap/incremental-marking.h b/src/heap/incremental-marking.h
index 0a3ad615aacf9303c3d31f78412d9344687745c6..56c5a24c2ceb732ab90bc1865da5bf184e5f46f8 100644
--- a/src/heap/incremental-marking.h
+++ b/src/heap/incremental-marking.h
@@ -48,6 +48,8 @@ class IncrementalMarking {
 
   bool ShouldActivate();
 
+  bool WasActivated();
+
   enum CompactionFlag { ALLOW_COMPACTION, PREVENT_COMPACTION };
 
   void Start(CompactionFlag flag = ALLOW_COMPACTION);
@@ -66,6 +68,8 @@ class IncrementalMarking {
 
   void MarkingComplete(CompletionAction action);
 
+  void Epilogue();
+
   // It's hard to know how much work the incremental marker should do to make
   // progress in the face of the mutator creating new work for it.  We start
   // of at a moderate rate of work and gradually increase the speed of the
@@ -222,6 +226,8 @@ class IncrementalMarking {
 
   int unscanned_bytes_of_large_object_;
 
+  bool was_activated_;
+
   DISALLOW_IMPLICIT_CONSTRUCTORS(IncrementalMarking);
 };
 }