Forward declare base::Time in uniformity trials.

Some fixes from a late code review for: https://codereview.chromium.org/12334124

Review URL: https://chromiumcodereview.appspot.com/12447006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@186253 0039d316-1c4b-4281-b951-d872f2087c98

chrome/common/metrics/variations/uniformity_field_trials.cc

@@ -6,6 +6,7 @@
 
 #include "base/metrics/field_trial.h"
 #include "base/stringprintf.h"
+#include "base/time.h"
 #include "chrome/common/metrics/variations/variations_util.h"
 
 namespace {
@@ -69,7 +70,7 @@ void SetupSingleUniformityFieldTrial(
 
 // 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) {
+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
@@ -92,7 +93,7 @@ void SetupNewInstallUniformityTrial(const base::Time& install_date) {
 
 namespace chrome_variations {
 
-void SetupUniformityFieldTrials(const base::Time& install_date) {
+void 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]|.

chrome/common/metrics/variations/uniformity_field_trials.h

-// Copyright (c) 2013 The Chromium Authors. All rights reserved.
+// Copyright 2013 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.
 
 #ifndef CHROME_COMMON_METRICS_VARIATIONS_UNIFORMITY_FIELD_TRIALS_H_
 #define CHROME_COMMON_METRICS_VARIATIONS_UNIFORMITY_FIELD_TRIALS_H_
 
-#include "base/time.h"
+namespace base {
+class Time;
+}
 
 namespace chrome_variations {
 
 // A collection of one-time-randomized and session-randomized field trials
 // intended to test the uniformity and correctness of the field trial control,
 // bucketing and reporting systems.
-void SetupUniformityFieldTrials(const base::Time& install_date);
+void SetupUniformityFieldTrials(const base::Time install_date);
 
 }  // namespace chrome_variations