Use stub impl when libcros fails to load

chrome/browser/chromeos/cros/screen_lock_library.cc

Index: chrome/browser/chromeos/cros/screen_lock_library.cc
diff --git a/chrome/browser/chromeos/cros/screen_lock_library.cc b/chrome/browser/chromeos/cros/screen_lock_library.cc
index fa6cbb83bd41cc039885227242fa6f93c1e209ab..53f80340f4e495928e7181045252d9fbddb067e6 100644
--- a/chrome/browser/chromeos/cros/screen_lock_library.cc
+++ b/chrome/browser/chromeos/cros/screen_lock_library.cc
@@ -28,10 +28,9 @@ class ScreenLockLibraryImpl : public ScreenLockLibrary {
 
   // Begin ScreenLockLibrary implementation.
   virtual void Init() OVERRIDE {
-    if (CrosLibrary::Get()->EnsureLoaded()) {
-      screen_lock_connection_ =
-          chromeos::MonitorScreenLock(&ScreenLockedHandler, this);
-    }
+    DCHECK(CrosLibrary::Get()->libcros_loaded());
+    screen_lock_connection_ =
+        chromeos::MonitorScreenLock(&ScreenLockedHandler, this);
   }
 
   virtual void AddObserver(Observer* observer) OVERRIDE {