Made possible to lock and unlock with several logged in users.

chrome/browser/chromeos/login/screen_locker_delegate.h

Index: chrome/browser/chromeos/login/screen_locker_delegate.h
diff --git a/chrome/browser/chromeos/login/screen_locker_delegate.h b/chrome/browser/chromeos/login/screen_locker_delegate.h
index 7c5e725eb8f2c5e6e7a1742fe2718096519af34f..96479193dc4cd79603ed9ff75bfe0e4ad7ff80a7 100644
--- a/chrome/browser/chromeos/login/screen_locker_delegate.h
+++ b/chrome/browser/chromeos/login/screen_locker_delegate.h
@@ -27,7 +27,7 @@ class ScreenLockerDelegate {
 
   // Initialize the screen locker delegate. This will call ScreenLockReady when
   // done to notify ScreenLocker.
-  virtual void LockScreen(bool unlock_on_input) = 0;
+  virtual void LockScreen() = 0;
 
   // Inform the screen locker that the screen has been locked
   virtual void ScreenLockReady();
@@ -60,6 +60,9 @@ class ScreenLockerDelegate {
   // there isn't one.
   virtual content::WebUI* GetAssociatedWebUI();
 
+  // Returns screen locker associated with delegate.
+  ScreenLocker* screen_locker() { return screen_locker_; }
+
  protected:
   // ScreenLocker that owns this delegate.
   ScreenLocker* screen_locker_;