Make transition to reduce memory mode more conservative in idle time handler.

src/heap/gc-idle-time-handler.h

 // Copyright 2014 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_GC_IDLE_TIME_HANDLER_H_
 #define V8_HEAP_GC_IDLE_TIME_HANDLER_H_
 
 #include "src/globals.h"
 
 namespace v8 {
@@ skipping 140 matching lines @@
   // The number of mutator GCs before transitioning to the kReduceLatency mode.
   static const int kGCsBeforeMutatorIsActive = 7;
 
   // Mutator is considered idle if
   // 1) there is an idle notification with time >= kLargeLongIdleTime,
   // 2) or there are kLongIdleNotificationsBeforeMutatorIsIdle idle
   // notifications
   //    with time >= kMinLongIdleTime and without any mutator GC in between.
   static const int kMinLongIdleTime = kMaxFrameRenderingIdleTime + 1;
   static const int kLargeLongIdleTime = 900;
-  static const int kLongIdleNotificationsBeforeMutatorIsIdle = 20;
+  static const int kLongIdleNotificationsBeforeMutatorIsIdle = 600;
 
 
   class HeapState {
    public:
     void Print();
 
     int contexts_disposed;
     double contexts_disposal_rate;
     size_t size_of_objects;
     bool incremental_marking_stopped;
@@ skipping 73 matching lines @@
 
   Mode mode_;
 
   DISALLOW_COPY_AND_ASSIGN(GCIdleTimeHandler);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_GC_IDLE_TIME_HANDLER_H_