Fix overflow in allocation throughput calculation.

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"
 
 namespace v8 {
@@ skipping 368 matching lines @@
 
   // Compute the average incremental mark-sweep finalize speed in
   // bytes/millisecond.
   // Returns 0 if no events have been recorded.
   intptr_t FinalIncrementalMarkCompactSpeedInBytesPerMillisecond() const;
 
   // Allocation throughput in the new space in bytes/millisecond.
   // Returns 0 if no allocation events have been recorded.
   size_t NewSpaceAllocationThroughputInBytesPerMillisecond() const;
 
-  // Bytes allocated in heap in the specified time.
+  // Allocation throughput in heap in bytes/millisecond in the last time_ms
+  // milliseconds.
   // Returns 0 if no allocation events have been recorded.
-  size_t AllocatedBytesInLast(double time_ms) const;
+  size_t AllocationThroughputInBytesPerMillisecond(double time_ms) const;
 
   // Allocation throughput in heap in bytes/milliseconds in
   // the last five seconds.
   // Returns 0 if no allocation events have been recorded.
   size_t CurrentAllocationThroughputInBytesPerMillisecond() 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.
@@ skipping 109 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_