Turned UiStrings into a singleton so that the continue window does not depend on ChromotingHost.

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 5a0975ebfc9b080e6a3797e82275fb17530550ad..60b4cac66751dc3a0b58250034ca8f2210b54203 100644
--- a/remoting/host/chromoting_host.h
+++ b/remoting/host/chromoting_host.h
@@ -17,7 +17,6 @@
 #include "remoting/host/host_key_pair.h"
 #include "remoting/host/host_status_observer.h"
 #include "remoting/host/mouse_move_observer.h"
-#include "remoting/host/ui_strings.h"
 #include "remoting/protocol/authenticator.h"
 #include "remoting/protocol/session_manager.h"
 #include "remoting/protocol/connection_to_client.h"
@@ -149,11 +148,6 @@ class ChromotingHost : public base::RefCountedThreadSafe<ChromotingHost>,
   // clients that were not connected when this method is called.
   void DisconnectAllClients();
 
-  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>;
   friend class ChromotingHostTest;
@@ -217,10 +211,6 @@ class ChromotingHost : public base::RefCountedThreadSafe<ChromotingHost>,
   // shutdown. Used only while |state_| is set to kStopping.
   std::vector<base::Closure> shutdown_tasks_;
 
-  // TODO(sergeyu): The following members do not belong to
-  // ChromotingHost and should be moved elsewhere.
-  UiStrings ui_strings_;
-
   // The maximum duration of any session.
   base::TimeDelta max_session_duration_;