[heap] Invoke incremental marking step before allocation.

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 c2290c4d8206ee39907d7d327baca35cb9e5db46..7f255244b508287889752e60bff10d17d4980350 100644
--- a/src/heap/incremental-marking.h
+++ b/src/heap/incremental-marking.h
@@ -99,6 +99,7 @@ class IncrementalMarking {
                                    CompletionAction completion_action,
                                    ForceCompletionAction force_completion,
                                    StepOrigin step_origin);
+  void AdvanceIncrementalMarkingOnAllocation();
 
   // 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
@@ -218,20 +219,6 @@ class IncrementalMarking {
   void AbortBlackAllocation();
 
  private:
-  class Observer : public AllocationObserver {
-   public:
-    Observer(IncrementalMarking& incremental_marking, intptr_t step_size)
-        : AllocationObserver(step_size),
-          incremental_marking_(incremental_marking) {}
-
-    void Step(int bytes_allocated, Address, size_t) override {
-      incremental_marking_.AdvanceIncrementalMarkingOnAllocation();
-    }
-
-   private:
-    IncrementalMarking& incremental_marking_;
-  };
-
   int64_t SpaceLeftInOldSpace();
 
   void StartMarking();
@@ -269,8 +256,6 @@ class IncrementalMarking {
 
   void IncrementIdleMarkingDelayCounter();
 
-  void AdvanceIncrementalMarkingOnAllocation();
-
   size_t StepSizeToKeepUpWithAllocations();
   size_t StepSizeToMakeProgress();
 
@@ -297,8 +282,6 @@ class IncrementalMarking {
   GCRequestType request_type_;
 
   IncrementalMarkingJob incremental_marking_job_;
-  Observer new_generation_observer_;
-  Observer old_generation_observer_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(IncrementalMarking);
 };