Update some uses of UTF conversions in chrome/browser to use the base:: namespace.

chrome/browser/ui/cocoa/ssl_client_certificate_selector_cocoa.mm

Index: chrome/browser/ui/cocoa/ssl_client_certificate_selector_cocoa.mm
diff --git a/chrome/browser/ui/cocoa/ssl_client_certificate_selector_cocoa.mm b/chrome/browser/ui/cocoa/ssl_client_certificate_selector_cocoa.mm
index 2a4830d1af552ca39a43109d1e96512f2cb9f638..c7ad387c0b82312886beeb1af53e222ad05465ea 100644
--- a/chrome/browser/ui/cocoa/ssl_client_certificate_selector_cocoa.mm
+++ b/chrome/browser/ui/cocoa/ssl_client_certificate_selector_cocoa.mm
@@ -143,7 +143,8 @@ void ShowSSLClientCertificateSelector(
   // Get the message to display:
   NSString* message = l10n_util::GetNSStringF(
       IDS_CLIENT_CERT_DIALOG_TEXT,
-      ASCIIToUTF16(observer_->cert_request_info()->host_and_port.ToString()));
+      base::ASCIIToUTF16(
+          observer_->cert_request_info()->host_and_port.ToString()));
 
   // Create and set up a system choose-identity panel.
   panel_.reset([[SFChooseIdentityPanel alloc] init]);