Move ObserverList to base namespace.

net/cert/nss_cert_database.h

Index: net/cert/nss_cert_database.h
diff --git a/net/cert/nss_cert_database.h b/net/cert/nss_cert_database.h
index 50eb037a2068aa7e1f33d3302d2bca2e56e5456f..b68a56dc697c90dc70ef7ab4e2c576045d847592 100644
--- a/net/cert/nss_cert_database.h
+++ b/net/cert/nss_cert_database.h
@@ -20,9 +20,10 @@
 #include "net/cert/x509_certificate.h"
 
 namespace base {
+template <class ObserverType>
+class ObserverListThreadSafe;
 class TaskRunner;
 }
-template <class ObserverType> class ObserverListThreadSafe;
 
 namespace net {
 
@@ -301,7 +302,7 @@ class NET_EXPORT NSSCertDatabase {
   // Task runner that should be used in tests if set.
   scoped_refptr<base::TaskRunner> slow_task_runner_for_test_;
 
-  const scoped_refptr<ObserverListThreadSafe<Observer> > observer_list_;
+  const scoped_refptr<base::ObserverListThreadSafe<Observer>> observer_list_;
 
   base::WeakPtrFactory<NSSCertDatabase> weak_factory_;