Remove SigninDelegateObserver.

ui/app_list/signin_delegate.cc

Index: ui/app_list/signin_delegate.cc
diff --git a/ui/app_list/signin_delegate.cc b/ui/app_list/signin_delegate.cc
index 93b0889daaf29e674a201d7aaacdfc57d79c0451..b0dd7e6759015c2a77efcc6c72c3392fe2b06dad 100644
--- a/ui/app_list/signin_delegate.cc
+++ b/ui/app_list/signin_delegate.cc
@@ -3,7 +3,6 @@
 // found in the LICENSE file.
 
 #include "ui/app_list/signin_delegate.h"
-#include "ui/app_list/signin_delegate_observer.h"
 
 namespace app_list {
 
@@ -11,16 +10,4 @@ SigninDelegate::SigninDelegate() {}
 
 SigninDelegate::~SigninDelegate() {}
 
-void SigninDelegate::AddObserver(SigninDelegateObserver* observer) {
-  observers_.AddObserver(observer);
-}
-
-void SigninDelegate::RemoveObserver(SigninDelegateObserver* observer) {
-  observers_.RemoveObserver(observer);
-}
-
-void SigninDelegate::NotifySigninSuccess() {
-  FOR_EACH_OBSERVER(SigninDelegateObserver, observers_, OnSigninSuccess());
-}
-
 }  // namespace app_list