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

chrome/browser/signin/easy_unlock_service_regular.cc

 // 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.
 
 #include "chrome/browser/signin/easy_unlock_service_regular.h"
 
 #include "base/bind.h"
 #include "base/logging.h"
 #include "base/prefs/pref_service.h"
 #include "base/prefs/scoped_user_pref_update.h"
@@ skipping 34 matching lines @@
 
 // Key name of the remote device list in kEasyUnlockPairing.
 const char kKeyDevices[] = "devices";
 
 }  // namespace
 
 EasyUnlockServiceRegular::EasyUnlockServiceRegular(Profile* profile)
     : EasyUnlockService(profile),
       turn_off_flow_status_(EasyUnlockService::IDLE),
       will_unlock_using_easy_unlock_(false),
+      lock_screen_last_shown_timestamp_(base::TimeTicks::Now()),
       weak_ptr_factory_(this) {
 }
 
 EasyUnlockServiceRegular::~EasyUnlockServiceRegular() {
 }
 
 EasyUnlockService::Type EasyUnlockServiceRegular::GetType() const {
   return EasyUnlockService::TYPE_REGULAR;
 }
 
@@ skipping 249 matching lines @@
 #else
   // TODO(xiyuan): Revisit when non-chromeos platforms are supported.
   return false;
 #endif
 }
 
 void EasyUnlockServiceRegular::OnWillFinalizeUnlock(bool success) {
   will_unlock_using_easy_unlock_ = success;
 }
 
+void EasyUnlockServiceRegular::OnSuspendDone() {
+  lock_screen_last_shown_timestamp_ = base::TimeTicks::Now();
+}
+
 void EasyUnlockServiceRegular::OnScreenDidLock(
     ScreenlockBridge::LockHandler::ScreenType screen_type) {
   will_unlock_using_easy_unlock_ = false;
+  lock_screen_last_shown_timestamp_ = base::TimeTicks::Now();
 }
 
 void EasyUnlockServiceRegular::OnScreenDidUnlock(
     ScreenlockBridge::LockHandler::ScreenType screen_type) {
   // Notifications of signin screen unlock events can also reach this code path;
   // disregard them.
   if (screen_type != ScreenlockBridge::LockHandler::LOCK_SCREEN)
     return;
 
   // Only record metrics for users who have enabled the feature.
   if (IsEnabled()) {
     EasyUnlockAuthEvent event =
         will_unlock_using_easy_unlock_
             ? EASY_UNLOCK_SUCCESS
             : GetPasswordAuthEvent();
     RecordEasyUnlockScreenUnlockEvent(event);
+
+    if (will_unlock_using_easy_unlock_) {
+      RecordEasyUnlockScreenUnlockDuration(
+          base::TimeTicks::Now() - lock_screen_last_shown_timestamp_);
+    }
   }
 
   will_unlock_using_easy_unlock_ = false;
 }
 
 void EasyUnlockServiceRegular::OnFocusedUserChanged(
     const std::string& user_id) {
   // Nothing to do.
 }
 
@@ skipping 35 matching lines @@
       new base::DictionaryValue());
   user_prefs_dict->SetBooleanWithoutPathExpansion(
       prefs::kEasyUnlockProximityRequired,
       profile_prefs->GetBoolean(prefs::kEasyUnlockProximityRequired));
 
   DictionaryPrefUpdate update(local_state,
                               prefs::kEasyUnlockLocalStateUserPrefs);
   std::string user_email = GetUserEmail();
   update->SetWithoutPathExpansion(user_email, user_prefs_dict.Pass());
 }