Clarify the strings in the external protocol dialog.

chrome/browser/ui/external_protocol_dialog_delegate.cc

Index: chrome/browser/ui/external_protocol_dialog_delegate.cc
diff --git a/chrome/browser/ui/external_protocol_dialog_delegate.cc b/chrome/browser/ui/external_protocol_dialog_delegate.cc
index 63c0b6517bfea33eb01665c1747f12ca9ffa49c7..2f2835608cdb0fb399741607ee843d57fe957d50 100644
--- a/chrome/browser/ui/external_protocol_dialog_delegate.cc
+++ b/chrome/browser/ui/external_protocol_dialog_delegate.cc
@@ -41,7 +41,7 @@ base::string16 ExternalProtocolDialogDelegate::GetDialogButtonLabel(
     return l10n_util::GetStringFUTF16(IDS_EXTERNAL_PROTOCOL_OK_BUTTON_TEXT,
                                       ElideCommandName(program_name_));
   }
-  return l10n_util::GetStringUTF16(IDS_CANCEL);
+  return l10n_util::GetStringUTF16(IDS_EXTERNAL_PROTOCOL_CANCEL_BUTTON_TEXT);
 }
 
 base::string16 ExternalProtocolDialogDelegate::GetMessageText() const {