[cros] Choose initial user avatar from new stock images only.

BUG=141142

Review URL: https://chromiumcodereview.appspot.com/10825318

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@151259 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/chromeos/login/user_manager_impl.cc

@@ -904,7 +904,8 @@ void UserManagerImpl::NotifyOnLogin() {
 
 void UserManagerImpl::SetInitialUserImage(const std::string& username) {
   // Choose a random default image.
-  int image_id = base::RandInt(0, kDefaultImagesCount - 1);
+  int image_id =
+      base::RandInt(kFirstDefaultImageIndex, kDefaultImagesCount - 1);
   SaveUserDefaultImageIndex(username, image_id);
 }