Make ChromotingHost::ui_strings() immutable.

remoting/host/chromoting_host.h

Index: remoting/host/chromoting_host.h
diff --git a/remoting/host/chromoting_host.h b/remoting/host/chromoting_host.h
index 0b8f29677b72ad6a7c615c73e22ac38caf378c50..fc35798263f783cf0c546e25993898c9d35ed1d7 100644
--- a/remoting/host/chromoting_host.h
+++ b/remoting/host/chromoting_host.h
@@ -145,7 +145,10 @@ class ChromotingHost : public base::RefCountedThreadSafe<ChromotingHost>,
   // is ignored.
   void PauseSession(bool pause);
 
-  UiStrings* ui_strings() { return &ui_strings_; }
+  const UiStrings& ui_strings() { return ui_strings_; }
+
+  // Set localized strings. Must be called before host is started.
+  void SetUiStrings(const UiStrings& ui_strings);
 
  private:
   friend class base::RefCountedThreadSafe<ChromotingHost>;