Move Singleton and related structs to namespace base

components/nacl/browser/pnacl_host.h

Index: components/nacl/browser/pnacl_host.h
diff --git a/components/nacl/browser/pnacl_host.h b/components/nacl/browser/pnacl_host.h
index d44d4b5cc5cc42cb200f222771005323dc8c60b1..28a00458046913e5074a3c24e05962c8bae669dc 100644
--- a/components/nacl/browser/pnacl_host.h
+++ b/components/nacl/browser/pnacl_host.h
@@ -101,7 +101,7 @@ class PnaclHost {
   // PnaclHost is a singleton because there is only one translation cache, and
   // so that the BrowsingDataRemover can clear it even if no translation has
   // ever been started.
-  friend struct DefaultSingletonTraits<PnaclHost>;
+  friend struct base::DefaultSingletonTraits<PnaclHost>;
   friend class FileProxy;
   friend class pnacl::PnaclHostTest;
   friend class pnacl::PnaclHostTestDisk;