Move uniformity trials to its own file.

chrome/browser/chrome_browser_field_trials.cc

Index: chrome/browser/chrome_browser_field_trials.cc
diff --git a/chrome/browser/chrome_browser_field_trials.cc b/chrome/browser/chrome_browser_field_trials.cc
index 100eb5719443abdfc881d4b2f60ea0981c8639ec..b7ee4885a2017386891ae8ae03395beaba3efd2d 100644
--- a/chrome/browser/chrome_browser_field_trials.cc
+++ b/chrome/browser/chrome_browser_field_trials.cc
@@ -24,6 +24,7 @@
 #include "chrome/browser/ui/sync/one_click_signin_helper.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/chrome_version_info.h"
+#include "chrome/common/metrics/variations/uniformity_field_trials.h"
 #include "chrome/common/metrics/variations/variations_util.h"
 #include "net/socket/client_socket_pool_base.h"
 #include "net/spdy/spdy_session.h"
@@ -36,84 +37,6 @@
 
 namespace {
 
-// Set up a uniformity field trial. |one_time_randomized| indicates if the
-// field trial is one-time randomized or session-randomized. |trial_name_string|
-// must contain a "%d" since the percentage of the group will be inserted in
-// the trial name. |num_trial_groups| must be a divisor of 100 (e.g. 5, 20)
-void SetupSingleUniformityFieldTrial(
-    bool one_time_randomized,
-    const std::string& trial_name_string,
-    const chrome_variations::VariationID trial_base_id,
-    int num_trial_groups) {
-  // Probability per group remains constant for all uniformity trials, what
-  // changes is the probability divisor.
-  static const base::FieldTrial::Probability kProbabilityPerGroup = 1;
-  const std::string kDefaultGroupName = "default";
-  const base::FieldTrial::Probability divisor = num_trial_groups;
-
-  DCHECK_EQ(100 % num_trial_groups, 0);
-  const int group_percent = 100 / num_trial_groups;
-  const std::string trial_name = StringPrintf(trial_name_string.c_str(),
-                                              group_percent);
-
-  DVLOG(1) << "Trial name = " << trial_name;
-
-  scoped_refptr<base::FieldTrial> trial(
-      base::FieldTrialList::FactoryGetFieldTrial(
-          trial_name, divisor, kDefaultGroupName, 2015, 1, 1, NULL));
-  if (one_time_randomized)
-    trial->UseOneTimeRandomization();
-  chrome_variations::AssociateGoogleVariationID(
-      chrome_variations::GOOGLE_WEB_PROPERTIES, trial_name, kDefaultGroupName,
-      trial_base_id);
-  chrome_variations::AssociateGoogleVariationID(
-      chrome_variations::GOOGLE_UPDATE_SERVICE, trial_name, kDefaultGroupName,
-      trial_base_id);
-
-  // 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 < num_trial_groups; ++group_number) {
-    const std::string group_name = StringPrintf("group_%02d", group_number);
-    DVLOG(1) << "    Group name = " << group_name;
-    trial->AppendGroup(group_name, kProbabilityPerGroup);
-    chrome_variations::AssociateGoogleVariationID(
-        chrome_variations::GOOGLE_WEB_PROPERTIES, trial_name, group_name,
-        static_cast<chrome_variations::VariationID>(trial_base_id +
-                                                    group_number));
-    chrome_variations::AssociateGoogleVariationID(
-        chrome_variations::GOOGLE_UPDATE_SERVICE, trial_name, group_name,
-        static_cast<chrome_variations::VariationID>(trial_base_id +
-                                                    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.
-  const int chosen_group = trial->group();
-  DVLOG(1) << "Chosen Group: " << chosen_group;
-}
-
-// Setup a 50% uniformity trial for new installs only. This is accomplished by
-// disabling the trial on clients that were installed before a specified date.
-void SetupNewInstallUniformityTrial(const base::Time& install_date) {
-  const base::Time::Exploded kStartDate = {
-    2012, 11, 0, 6,  // Nov 6, 2012
-    0, 0, 0, 0       // 00:00:00.000
-  };
-  scoped_refptr<base::FieldTrial> trial(
-      base::FieldTrialList::FactoryGetFieldTrial(
-          "UMA-New-Install-Uniformity-Trial", 100, "Disabled",
-          2015, 1, 1, NULL));
-  trial->UseOneTimeRandomization();
-  trial->AppendGroup("Control", 50);
-  trial->AppendGroup("Experiment", 50);
-  const base::Time start_date = base::Time::FromLocalExploded(kStartDate);
-  if (install_date < start_date)
-    trial->Disable();
-  else
-    trial->group();
-}
-
 void SetSocketReusePolicy(int warmest_socket_trial_group,
                           const int socket_policy[],
                           int num_groups) {
@@ -136,7 +59,7 @@ ChromeBrowserFieldTrials::~ChromeBrowserFieldTrials() {
 
 void ChromeBrowserFieldTrials::SetupFieldTrials(
     const base::Time& install_time) {
-  SetupUniformityFieldTrials(install_time);
+  chrome_variations::SetupUniformityFieldTrials(install_time);
 #if !defined(OS_ANDROID)
   SetupDesktopFieldTrials();
 #endif  // defined(OS_ANDROID)
@@ -242,40 +165,6 @@ void ChromeBrowserFieldTrials::AutoLaunchChromeFieldTrial() {
   }
 }
 
-void ChromeBrowserFieldTrials::SetupUniformityFieldTrials(
-    const base::Time& install_date) {
-  // One field trial will be created for each entry in this array. The i'th
-  // field trial will have |trial_sizes[i]| groups in it, including the default
-  // group. Each group will have a probability of 1/|trial_sizes[i]|.
-  const int num_trial_groups[] = { 100, 20, 10, 5, 2 };
-
-  // Declare our variation ID bases along side this array so we can loop over it
-  // and assign the IDs appropriately. So for example, the 1 percent experiments
-  // should have a size of 100 (100/100 = 1).
-  const chrome_variations::VariationID trial_base_ids[] = {
-      chrome_variations::UNIFORMITY_1_PERCENT_BASE,
-      chrome_variations::UNIFORMITY_5_PERCENT_BASE,
-      chrome_variations::UNIFORMITY_10_PERCENT_BASE,
-      chrome_variations::UNIFORMITY_20_PERCENT_BASE,
-      chrome_variations::UNIFORMITY_50_PERCENT_BASE
-  };
-
-  const std::string kOneTimeRandomizedTrialName =
-      "UMA-Uniformity-Trial-%d-Percent";
-  for (size_t i = 0; i < arraysize(num_trial_groups); ++i) {
-    SetupSingleUniformityFieldTrial(true, kOneTimeRandomizedTrialName,
-                                       trial_base_ids[i], num_trial_groups[i]);
-  }
-
-  // Setup a 5% session-randomized uniformity trial.
-  const std::string kSessionRandomizedTrialName =
-      "UMA-Session-Randomized-Uniformity-Trial-%d-Percent";
-  SetupSingleUniformityFieldTrial(false, kSessionRandomizedTrialName,
-      chrome_variations::UNIFORMITY_SESSION_RANDOMIZED_5_PERCENT_BASE, 20);
-
-  SetupNewInstallUniformityTrial(install_date);
-}
-
 void ChromeBrowserFieldTrials::DisableNewTabFieldTrialIfNecesssary() {
   // The new tab button field trial will get created in variations_service.cc
   // through the variations server. However, since there are no HiDPI assets