Add base:: to string16s in sandbox/.

sandbox/win/src/app_container_test.cc

Index: sandbox/win/src/app_container_test.cc
diff --git a/sandbox/win/src/app_container_test.cc b/sandbox/win/src/app_container_test.cc
index 3b33ca5c9010753aebe42f476ce18aa53a8366be..1bfab2c3145b3c91a69634049d9c652c480770c8 100644
--- a/sandbox/win/src/app_container_test.cc
+++ b/sandbox/win/src/app_container_test.cc
@@ -23,7 +23,8 @@ const wchar_t kAppContainerSid[] =
 
 const ULONG kSharing = FILE_SHARE_WRITE | FILE_SHARE_READ | FILE_SHARE_DELETE;
 
-HANDLE CreateTaggedEvent(const string16& name, const string16& sid) {
+HANDLE CreateTaggedEvent(const base::string16& name,
+                         const base::string16& sid) {
   base::win::ScopedHandle event(CreateEvent(NULL, FALSE, FALSE, name.c_str()));
   if (!event.IsValid())
     return NULL;