Use actual incremental marking throughput in IdleNotification to estimate marking step size.

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 "src/allocation.h"
@@ skipping 1050 matching lines @@
                                         int freed_global_handles);
 
   // Indicates whether inline bump-pointer allocation has been disabled.
   bool inline_allocation_disabled() { return inline_allocation_disabled_; }
 
   // Switch whether inline bump-pointer allocation should be used.
   void EnableInlineAllocation();
   void DisableInlineAllocation();
 
   // Implements the corresponding V8 API function.
-  bool IdleNotification(int hint);
+  bool IdleNotification(int idle_time_in_ms);
 
   // Declare all the root indices.  This defines the root list order.
   enum RootListIndex {
 #define ROOT_INDEX_DECLARATION(type, name, camel_name) k##camel_name##RootIndex,
     STRONG_ROOT_LIST(ROOT_INDEX_DECLARATION)
 #undef ROOT_INDEX_DECLARATION
 
 #define STRING_INDEX_DECLARATION(name, str) k##name##RootIndex,
     INTERNALIZED_STRING_LIST(STRING_INDEX_DECLARATION)
 #undef STRING_DECLARATION
@@ skipping 1456 matching lines @@
   DisallowHeapAllocation no_allocation;  // i.e. no gc allowed.
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(PathTracer);
 };
 #endif  // DEBUG
 }
 }  // namespace v8::internal
 
 #endif  // V8_HEAP_HEAP_H_