Revert "Track history of events in GCTracer."

src/incremental-marking.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_INCREMENTAL_MARKING_H_
 #define V8_INCREMENTAL_MARKING_H_
 
 
 #include "src/execution.h"
 #include "src/mark-compact.h"
@@ skipping 118 matching lines @@
   void RecordWriteOfCodeEntrySlow(JSFunction* host, Object** slot, Code* value);
   void RecordCodeTargetPatch(Code* host, Address pc, HeapObject* value);
   void RecordCodeTargetPatch(Address pc, HeapObject* value);
 
   inline void RecordWrites(HeapObject* obj);
 
   inline void BlackToGreyAndUnshift(HeapObject* obj, MarkBit mark_bit);
 
   inline void WhiteToGreyAndPush(HeapObject* obj, MarkBit mark_bit);
 
+  inline int steps_count() { return steps_count_; }
+
+  inline double steps_took() { return steps_took_; }
+
+  inline double longest_step() { return longest_step_; }
+
+  inline int steps_count_since_last_gc() { return steps_count_since_last_gc_; }
+
+  inline double steps_took_since_last_gc() { return steps_took_since_last_gc_; }
+
   inline void SetOldSpacePageFlags(MemoryChunk* chunk) {
     SetOldSpacePageFlags(chunk, IsMarking(), IsCompacting());
   }
 
   inline void SetNewSpacePageFlags(NewSpacePage* chunk) {
     SetNewSpacePageFlags(chunk, IsMarking());
   }
 
   MarkingDeque* marking_deque() { return &marking_deque_; }
 
@@ skipping 60 matching lines @@
   Heap* heap_;
 
   State state_;
   bool is_compacting_;
 
   base::VirtualMemory* marking_deque_memory_;
   bool marking_deque_memory_committed_;
   MarkingDeque marking_deque_;
 
   int steps_count_;
+  double steps_took_;
+  double longest_step_;
   int64_t old_generation_space_available_at_start_of_incremental_;
   int64_t old_generation_space_used_at_start_of_incremental_;
+  int steps_count_since_last_gc_;
+  double steps_took_since_last_gc_;
   int64_t bytes_rescanned_;
   bool should_hurry_;
   int marking_speed_;
   intptr_t bytes_scanned_;
   intptr_t allocated_;
   intptr_t write_barriers_invoked_since_last_step_;
 
   int no_marking_scope_depth_;
 
   int unscanned_bytes_of_large_object_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(IncrementalMarking);
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_INCREMENTAL_MARKING_H_