[heap] Fix comment in tracer.

src/heap/gc-tracer.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_TRACER_H_
 #define V8_HEAP_GC_TRACER_H_
 
 #include "src/base/platform/platform.h"
 #include "src/globals.h"
 
@@ skipping 401 matching lines @@
   // last time_ms milliseconds.
   // Returns 0 if no allocation events have been recorded.
   size_t OldGenerationAllocationThroughputInBytesPerMillisecond(
       double time_ms = 0) const;
 
   // Allocation throughput in heap in bytes/millisecond in the last time_ms
   // milliseconds.
   // Returns 0 if no allocation events have been recorded.
   size_t AllocationThroughputInBytesPerMillisecond(double time_ms) const;
 
-  // Allocation throughput in heap in bytes/milliseconds in
-  // the last five seconds.
+  // Allocation throughput in heap in bytes/milliseconds in the last
+  // kThroughputTimeFrameMs seconds.
   // Returns 0 if no allocation events have been recorded.
   size_t CurrentAllocationThroughputInBytesPerMillisecond() const;
 
-  // Allocation throughput in old generation in bytes/milliseconds in
-  // the last five seconds.
+  // Allocation throughput in old generation in bytes/milliseconds in the last
+  // kThroughputTimeFrameMs seconds.
   // Returns 0 if no allocation events have been recorded.
   size_t CurrentOldGenerationAllocationThroughputInBytesPerMillisecond() const;
 
   // Computes the context disposal rate in milliseconds. It takes the time
   // frame of the first recorded context disposal to the current time and
   // divides it by the number of recorded events.
   // Returns 0 if no events have been recorded.
   double ContextDisposalRateInMilliseconds() const;
 
   // Computes the average survival ratio based on the last recorded survival
@@ skipping 112 matching lines @@
 
   // Counts how many tracers were started without stopping.
   int start_counter_;
 
   DISALLOW_COPY_AND_ASSIGN(GCTracer);
 };
 }
 }  // namespace v8::internal
 
 #endif  // V8_HEAP_GC_TRACER_H_