Remove the remaining parts of background idle notification.

src/heap/heap.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_HEAP_HEAP_H_
 #define V8_HEAP_HEAP_H_
 
 #include <cmath>
 #include <map>
 
@@ skipping 1783 matching lines @@
 
   GCIdleTimeHeapState ComputeHeapState();
 
   bool PerformIdleTimeAction(GCIdleTimeAction action,
                              GCIdleTimeHeapState heap_state,
                              double deadline_in_ms);
 
   void IdleNotificationEpilogue(GCIdleTimeAction action,
                                 GCIdleTimeHeapState heap_state, double start_ms,
                                 double deadline_in_ms);
-  void CheckBackgroundIdleNotification(double idle_time_in_ms, double now_ms);
 
   inline void UpdateAllocationsHash(HeapObject* object);
   inline void UpdateAllocationsHash(uint32_t value);
   void PrintAlloctionsHash();
 
   void AddToRingBuffer(const char* string);
   void GetFromRingBuffer(char* buffer);
 
   // Attempt to over-approximate the weak closure by marking object groups and
   // implicit references from global handles, but don't atomically complete
@@ skipping 913 matching lines @@
   DisallowHeapAllocation no_allocation;  // i.e. no gc allowed.
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(PathTracer);
 };
 #endif  // DEBUG
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_HEAP_H_