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

src/heap/gc-tracer.cc

Index: src/heap/gc-tracer.cc
diff --git a/src/heap/gc-tracer.cc b/src/heap/gc-tracer.cc
index a231a8eea2f57b4d1703a486bbd570ded0141a85..454b3ac0b05ad72fca6c5bf7841c37c7aaac2d58 100644
--- a/src/heap/gc-tracer.cc
+++ b/src/heap/gc-tracer.cc
@@ -702,11 +702,17 @@ size_t GCTracer::AllocationThroughputInBytesPerMillisecond(
 }
 
 
+size_t GCTracer::CurrentNewSpaceAllocationThroughputInBytesPerMillisecond()
+    const {
+  return NewSpaceAllocationThroughputInBytesPerMillisecond(
+      kThroughputTimeFrameMs);
+}
+
+
 size_t GCTracer::CurrentOldGenerationAllocationThroughputInBytesPerMillisecond()
     const {
-  static const double kThroughputTimeFrame = 5000;
   return OldGenerationAllocationThroughputInBytesPerMillisecond(
-      kThroughputTimeFrame);
+      kThroughputTimeFrameMs);
 }