Keep unlogged-samples object for minidump.

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 596 matching lines @@
 }
 
 std::unique_ptr<SampleVector> Histogram::SnapshotAllSamples() const {
   std::unique_ptr<SampleVector> samples = SnapshotUnloggedSamples();
   samples->Add(*logged_samples_);
   return samples;
 }
 
 std::unique_ptr<SampleVector> Histogram::SnapshotUnloggedSamples() const {
   // TODO(bcwhite): Remove these CHECKs once crbug/734049 is resolved.
+  HistogramSamples* unlogged = unlogged_samples_.get();
   CHECK(unlogged_samples_);
   CHECK(unlogged_samples_->id());
   CHECK(bucket_ranges());
   std::unique_ptr<SampleVector> samples(
       new SampleVector(unlogged_samples_->id(), bucket_ranges()));
   samples->Add(*unlogged_samples_);
+  debug::Alias(&unlogged);
   return samples;
 }
 
 void Histogram::WriteAsciiImpl(bool graph_it,
                                const std::string& newline,
                                std::string* output) const {
   // Get local (stack) copies of all effectively volatile class data so that we
   // are consistent across our output activities.
   std::unique_ptr<SampleVector> snapshot = SnapshotAllSamples();
   Count sample_count = snapshot->TotalCount();
@@ skipping 588 matching lines @@
     Sample sample = custom_ranges[i];
     if (sample < 0 || sample > HistogramBase::kSampleType_MAX - 1)
       return false;
     if (sample != 0)
       has_valid_range = true;
   }
   return has_valid_range;
 }
 
 }  // namespace base