[Smart Lock] Add UMA metrics to measure duration of unlock.

chrome/browser/signin/easy_unlock_metrics.h

 // Copyright 2014 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_BROWSER_SIGNIN_EASY_UNLOCK_METRICS_H_
 #define CHROME_BROWSER_SIGNIN_EASY_UNLOCK_METRICS_H_
 
+namespace base {
+class TimeDelta;
+}
+
 // Tracking login events for Easy unlock metrics.
 // This enum is used to define the buckets for an enumerated UMA histogram.
 // Hence,
 //   (a) existing enumerated constants should never be deleted or reordered, and
 //   (b) new constants should only be appended at the end of the enumeration.
 enum EasyUnlockAuthEvent {
   // User is successfully authenticated using Easy Unlock.
   EASY_UNLOCK_SUCCESS = 0,
   // Easy Unlock failed to authenticate the user.
   EASY_UNLOCK_FAILURE = 1,
@@ skipping 44 matching lines @@
 };
 
 enum EasyUnlockTrialRunEvent {
   // A trial run was initiated from the Easy Unlock setup app.
   EASY_UNLOCK_TRIAL_RUN_EVENT_LAUNCHED = 0,
   // The user clicked on the lock icon during the trial run.
   EASY_UNLOCK_TRIAL_RUN_EVENT_CLICKED_LOCK_ICON = 1,
   EASY_UNLOCK_TRIAL_RUN_EVENT_COUNT  // Must be the last entry.
 };
 
+void RecordEasyUnlockSigninDuration(const base::TimeDelta& duration);
 void RecordEasyUnlockSigninEvent(EasyUnlockAuthEvent event);
+void RecordEasyUnlockScreenUnlockDuration(const base::TimeDelta& duration);
 void RecordEasyUnlockScreenUnlockEvent(EasyUnlockAuthEvent event);
 void RecordEasyUnlockTrialRunEvent(EasyUnlockTrialRunEvent event);
 
 #endif  // CHROME_BROWSER_SIGNIN_EASY_UNLOCK_METRICS_H_