Remove some pass-thrus on RootWindow API in favor of exposing the RootWindowHost again.

ash/test/ash_test_base.cc

Index: ash/test/ash_test_base.cc
diff --git a/ash/test/ash_test_base.cc b/ash/test/ash_test_base.cc
index b50dba2b1002342e8bc109e3a99f7225a42b1c70..be27c7d01e75d393926a8f31ba141b5ca0302baa 100644
--- a/ash/test/ash_test_base.cc
+++ b/ash/test/ash_test_base.cc
@@ -121,7 +121,7 @@ void AshTestBase::SetUp() {
   ash_test_helper_->SetUp(start_session_);
 
   Shell::GetPrimaryRootWindow()->Show();
-  Shell::GetPrimaryRootWindow()->GetDispatcher()->ShowRootWindow();
+  Shell::GetPrimaryRootWindow()->GetDispatcher()->host()->Show();
   // Move the mouse cursor to far away so that native events doesn't
   // interfere test expectations.
   Shell::GetPrimaryRootWindow()->MoveCursorTo(gfx::Point(-1000, -1000));