Re-enable pre-read experiment as a finch field trial.

base/metrics/histogram.h

 // 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).
 
 // It supports calls to accumulate either time intervals (which are processed
 // as integral number of milliseconds), or arbitrary integral units.
@@ skipping 289 matching lines @@
 
 #define UMA_HISTOGRAM_MEDIUM_TIMES(name, sample) UMA_HISTOGRAM_CUSTOM_TIMES( \
     name, sample, base::TimeDelta::FromMilliseconds(10), \
     base::TimeDelta::FromMinutes(3), 50)
 
 // Use this macro when times can routinely be much longer than 10 seconds.
 #define UMA_HISTOGRAM_LONG_TIMES(name, sample) UMA_HISTOGRAM_CUSTOM_TIMES( \
     name, sample, base::TimeDelta::FromMilliseconds(1), \
     base::TimeDelta::FromHours(1), 50)
 
+// Use this macro when times can routinely be much longer than 10 seconds and
+// you want 100 buckets.
+#define UMA_HISTOGRAM_LONG_TIMES_100(name, sample) UMA_HISTOGRAM_CUSTOM_TIMES( \
+    name, sample, base::TimeDelta::FromMilliseconds(1), \
+    base::TimeDelta::FromHours(1), 100)
+
 #define UMA_HISTOGRAM_CUSTOM_TIMES(name, sample, min, max, bucket_count) \
     STATIC_HISTOGRAM_POINTER_BLOCK(name, AddTime(sample), \
         base::Histogram::FactoryTimeGet(name, min, max, bucket_count, \
             base::HistogramBase::kUmaTargetedHistogramFlag))
 
 #define UMA_HISTOGRAM_COUNTS(name, sample) UMA_HISTOGRAM_CUSTOM_COUNTS( \
     name, sample, 1, 1000000, 50)
 
 #define UMA_HISTOGRAM_COUNTS_100(name, sample) UMA_HISTOGRAM_CUSTOM_COUNTS( \
     name, sample, 1, 100, 50)
@@ skipping 346 matching lines @@
   static bool ValidateCustomRanges(const std::vector<Sample>& custom_ranges);
   static BucketRanges* CreateBucketRangesFromCustomRanges(
       const std::vector<Sample>& custom_ranges);
 
   DISALLOW_COPY_AND_ASSIGN(CustomHistogram);
 };
 
 }  // namespace base
 
 #endif  // BASE_METRICS_HISTOGRAM_H_