Factor out a Histogram class from HistogramTimer, and use it to measure external fragmentation

src/v8-counters.cc

-// Copyright 2007-2008 the V8 project authors. All rights reserved.
+// Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
 //       with the distribution.
@@ skipping 15 matching lines @@
 
 #include "v8.h"
 
 #include "v8-counters.h"
 
 namespace v8 {
 namespace internal {
 
 Counters::Counters() {
 #define HT(name, caption) \
-    HistogramTimer name = { #caption, NULL, false, 0, 0 }; \
+    HistogramTimer name = { {#caption, 0, 10000, 50, NULL, false}, 0, 0 }; \
     name##_ = name;
     HISTOGRAM_TIMER_LIST(HT)
 #undef HT
 
+#define HP(name, caption) \
+    Histogram name = { #caption, 0, 101, 100, NULL, false }; \
+    name##_ = name;
+    HISTOGRAM_PERCENTAGE_LIST(HP)
+#undef HP
+
 #define SC(name, caption) \
     StatsCounter name = { "c:" #caption, NULL, false };\
     name##_ = name;
 
     STATS_COUNTER_LIST_1(SC)
     STATS_COUNTER_LIST_2(SC)
 #undef SC
 
   StatsCounter state_counters[] = {
 #define COUNTER_NAME(name) \
     { "c:V8.State" #name, NULL, false },
     STATE_TAG_LIST(COUNTER_NAME)
 #undef COUNTER_NAME
   };
 
   for (int i = 0; i < kSlidingStateWindowCounterCount; ++i) {
     state_counters_[i] = state_counters[i];
   }
 }
 
 } }  // namespace v8::internal