Memory reducer should use the current allocation rate instead of the overall allocation rate.

src/heap/gc-tracer.h

Index: src/heap/gc-tracer.h
diff --git a/src/heap/gc-tracer.h b/src/heap/gc-tracer.h
index 811266e92e29c4fbf45fc980db58fe72eaec1ac4..7359b14183335f109c0459296a405eb959ab0816 100644
--- a/src/heap/gc-tracer.h
+++ b/src/heap/gc-tracer.h
@@ -288,6 +288,8 @@ class GCTracer {
     double scopes[Scope::NUMBER_OF_SCOPES];
   };
 
+  static const int kThroughputTimeFrameMs = 5000;
+
   static const size_t kRingBufferMaxSize = 10;
 
   typedef RingBuffer<Event, kRingBufferMaxSize> EventBuffer;
@@ -416,6 +418,11 @@ class GCTracer {
   // Returns 0 if no allocation events have been recorded.
   size_t AllocationThroughputInBytesPerMillisecond(double time_ms) const;
 
+  // Allocation throughput in new space in bytes/milliseconds in
+  // the last five seconds.
+  // Returns 0 if no allocation events have been recorded.
+  size_t CurrentNewSpaceAllocationThroughputInBytesPerMillisecond() const;
+
   // Allocation throughput in old generation in bytes/milliseconds in
   // the last five seconds.
   // Returns 0 if no allocation events have been recorded.