first pass histogram shrink

base/metrics/histogram.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Histogram is an object that aggregates statistics, and can summarize them in
 // various forms, including ASCII graphical, HTML, and numerically (as a
 // vector of numbers corresponding to each of the aggregating buckets).
 // See header file for details and examples.
 
 #include "base/metrics/histogram.h"
@@ skipping 105 matching lines @@
 
 HistogramBase* Histogram::FactoryTimeGet(const string& name,
                                          TimeDelta minimum,
                                          TimeDelta maximum,
                                          size_t bucket_count,
                                          int32 flags) {
   return FactoryGet(name, minimum.InMilliseconds(), maximum.InMilliseconds(),
                     bucket_count, flags);
 }
 
+HistogramBase* Histogram::FactoryTimeGetAndAtomicRelease(
+    base::subtle::AtomicWord* atomic_histogram_pointer,
+    const string& name,
+                                         TimeDelta minimum,
+                                         TimeDelta maximum,
+                                         size_t bucket_count,
+                                         int32 flags) {
+  HistogramBase* retval = FactoryGet(name, minimum.InMilliseconds(), maximum.InMilliseconds(),
+                                     bucket_count, flags);
+  base::subtle::Release_Store(atomic_histogram_pointer,
+                              reinterpret_cast<base::subtle::AtomicWord>(retval));
+  return retval;
+}
+
 TimeTicks Histogram::DebugNow() {
 #ifndef NDEBUG
   return TimeTicks::Now();
 #else
   return TimeTicks();
 #endif
 }
 
 // Calculate what range of values are held in each bucket.
 // We have to be careful that we don't pick a ratio between starting points in
@@ skipping 689 matching lines @@
 
   BucketRanges* bucket_ranges = new BucketRanges(ranges.size());
   for (size_t i = 0; i < ranges.size(); i++) {
     bucket_ranges->set_range(i, ranges[i]);
   }
   bucket_ranges->ResetChecksum();
   return bucket_ranges;
 }
 
 }  // namespace base