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

chrome/browser/signin/easy_unlock_service_regular.h

Index: chrome/browser/signin/easy_unlock_service_regular.h
diff --git a/chrome/browser/signin/easy_unlock_service_regular.h b/chrome/browser/signin/easy_unlock_service_regular.h
index 6b34afef928865ae1645806a167e58b3ba03188d..c748cd60654330f7eb01696678d32bf4030e004e 100644
--- a/chrome/browser/signin/easy_unlock_service_regular.h
+++ b/chrome/browser/signin/easy_unlock_service_regular.h
@@ -11,11 +11,13 @@
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/prefs/pref_change_registrar.h"
+#include "base/time/time.h"
 #include "chrome/browser/signin/easy_unlock_service.h"
 #include "chrome/browser/signin/screenlock_bridge.h"
 
 #if defined(OS_CHROMEOS)
 #include "chrome/browser/chromeos/login/easy_unlock/short_lived_user_context.h"
+#include "chromeos/dbus/power_manager_client.h"
 #endif
 
 namespace base {
@@ -38,6 +40,9 @@ class Profile;
 // EasyUnlockService instance that should be used for regular, non-signin
 // profiles.
 class EasyUnlockServiceRegular : public EasyUnlockService,
+#if defined(OS_CHROMEOS)
+                                 public chromeos::PowerManagerClient::Observer,

[Tim Song, 2015/03/25 18:17:28]

The base class has a similar observer in EasyUnlockService::PowerMonitor.
Perhaps you can call a virtual method from the base class when resuming from
suspend instead of adding this observer?

[Ilya Sherman, 2015/04/01 00:16:13]

Done.

+#endif
                                  public ScreenlockBridge::Observer {
  public:
   explicit EasyUnlockServiceRegular(Profile* profile);
@@ -75,6 +80,11 @@ class EasyUnlockServiceRegular : public EasyUnlockService,
       ScreenlockBridge::LockHandler::ScreenType screen_type) override;
   void OnFocusedUserChanged(const std::string& user_id) override;
 
+#if defined(OS_CHROMEOS)
+  // chromeos::PowerManagerClient::Observer implementation:
+  void SuspendDone(const base::TimeDelta& sleep_duration) override;
+#endif  // defined(OS_CHROMEOS)
+
   // Callback when the controlling pref changes.
   void OnPrefsChanged();
 
@@ -116,6 +126,12 @@ class EasyUnlockServiceRegular : public EasyUnlockService,
   // password-based unlocks for metrics.
   bool will_unlock_using_easy_unlock_;
 
+  // The timestamp for the most recent time when the lock screen was shown. The
+  // lock screen is typically shown when the user awakens her computer from
+  // sleep -- e.g. by opening the lid -- but can also be shown if the screen is
+  // locked but the computer does not go to sleep.
+  base::TimeTicks lock_screen_last_shown_timestamp_;
+
   base::WeakPtrFactory<EasyUnlockServiceRegular> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(EasyUnlockServiceRegular);