Merge 135655 - Uselessly use the uniformity field trial.

chrome/browser/chrome_browser_main.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.
 
 #include "chrome/browser/chrome_browser_main.h"
 
 #include <algorithm>
 #include <string>
 #include <vector>
 
@@ skipping 1063 matching lines @@
         trial_base_ids[i]);
     // Loop starts with group 1 because the field trial automatically creates a
     // default group, which would be group 0.
     for (int group_number = 1; group_number < trial_sizes[i]; ++group_number) {
       const std::string group_name = StringPrintf("group_%02d", group_number);
       DVLOG(1) << "    Group name = " << group_name;
       trial->AppendGroup(group_name, kProbabilityPerGroup);
       experiments_helper::AssociateGoogleExperimentID(trial_name, group_name,
           static_cast<chrome_variations::ID>(trial_base_ids[i] + group_number));
     }
+
+    // Now that all groups have been appended, call group() on the trial to
+    // ensure that our trial is registered. This resolves an off-by-one issue
+    // where the default group never gets chosen if we don't "use" the trial.
+    int chosen_group = trial->group();
+    DVLOG(1) << "Chosen Group: " << chosen_group;
   }
 }
 
 // ChromeBrowserMainParts: |SetupMetricsAndFieldTrials()| related --------------
 
 void ChromeBrowserMainParts::SetupFieldTrials(bool metrics_recording_enabled,
                                               bool proxy_policy_is_set) {
   // Note: make sure to call ConnectionFieldTrial() before
   // ProxyConnectionsFieldTrial().
   ConnectionFieldTrial();
@@ skipping 909 matching lines @@
     if (base::win::GetVersion() <= base::win::VERSION_XP)
       uma_name += "_XP";
 
     uma_name += "_PreRead_";
     uma_name += pre_read_percentage;
     AddPreReadHistogramTime(uma_name.c_str(), time);
   }
 #endif
 #endif
 }