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

chrome/browser/signin/easy_unlock_service.h

Index: chrome/browser/signin/easy_unlock_service.h
diff --git a/chrome/browser/signin/easy_unlock_service.h b/chrome/browser/signin/easy_unlock_service.h
index 649c0aeccf0ee133a769f003022a7f6d71a5e44c..4824a954ac81a4273591c450e25c6fcefdf85636 100644
--- a/chrome/browser/signin/easy_unlock_service.h
+++ b/chrome/browser/signin/easy_unlock_service.h
@@ -232,6 +232,9 @@ class EasyUnlockService : public KeyedService {
   // Unlock, just before the screen is unlocked.
   virtual void OnWillFinalizeUnlock(bool success) = 0;
 
+  // Called when the local device resumes after a suspend.
+  virtual void OnSuspendDone() = 0;
+
   // KeyedService override:
   void Shutdown() override;