Move ObserverList to base namespace.

net/cert/cert_database.h

Index: net/cert/cert_database.h
diff --git a/net/cert/cert_database.h b/net/cert/cert_database.h
index 3653e81b1fb38120c29b7692db4ec816122fbfdf..fb28c897772b3a28f1d1d658d1c4d5bf71c25672 100644
--- a/net/cert/cert_database.h
+++ b/net/cert/cert_database.h
@@ -12,7 +12,10 @@
 #include "net/cert/x509_certificate.h"
 
 template <typename T> struct DefaultSingletonTraits;
+
+namespace base {
 template <class ObserverType> class ObserverListThreadSafe;
+}
 
 namespace net {
 
@@ -106,7 +109,7 @@ class NET_EXPORT CertDatabase {
   CertDatabase();
   ~CertDatabase();
 
-  const scoped_refptr<ObserverListThreadSafe<Observer> > observer_list_;
+  const scoped_refptr<base::ObserverListThreadSafe<Observer>> observer_list_;
 
 #if defined(OS_MACOSX) && !defined(OS_IOS)
   class Notifier;