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

remoting/host/host_mock_objects.cc

Index: remoting/host/host_mock_objects.cc
diff --git a/remoting/host/host_mock_objects.cc b/remoting/host/host_mock_objects.cc
index f9b6c52a523894cf4e7e57bad03754a3a157b188..b6f86b4458c17df93ff6e202fb86f2012504a61c 100644
--- a/remoting/host/host_mock_objects.cc
+++ b/remoting/host/host_mock_objects.cc
@@ -35,7 +35,8 @@ MockDisconnectWindow::MockDisconnectWindow() {}
 
 MockDisconnectWindow::~MockDisconnectWindow() {}
 
-scoped_ptr<DisconnectWindow> DisconnectWindow::Create() {
+scoped_ptr<DisconnectWindow> DisconnectWindow::Create(
+    const UiStrings* ui_strings) {
   return scoped_ptr<DisconnectWindow>(new MockDisconnectWindow());
 }
 
@@ -43,7 +44,7 @@ MockContinueWindow::MockContinueWindow() {}
 
 MockContinueWindow::~MockContinueWindow() {}
 
-scoped_ptr<ContinueWindow> ContinueWindow::Create() {
+scoped_ptr<ContinueWindow> ContinueWindow::Create(const UiStrings* ui_strings) {
   return scoped_ptr<ContinueWindow>(new MockContinueWindow());
 }