ash: Use SessionController instead of SessionStateDelegate

ash/wm/always_on_top_controller_unittest.cc

Index: ash/wm/always_on_top_controller_unittest.cc
diff --git a/ash/wm/always_on_top_controller_unittest.cc b/ash/wm/always_on_top_controller_unittest.cc
index 54dad323884248f1081ce006e7e5acc918e942e7..4ee77dfe34c721cc9bde8354c598a447220f0a65 100644
--- a/ash/wm/always_on_top_controller_unittest.cc
+++ b/ash/wm/always_on_top_controller_unittest.cc
@@ -66,6 +66,8 @@ TEST_F(VirtualKeyboardAlwaysOnTopControllerTest, NotifyKeyboardBoundsChanged) {
   TestLayoutManager* manager =
       new TestLayoutManager(WmWindow::Get(always_on_top_container));
   RootWindowController* controller = Shell::GetPrimaryRootWindowController();
+  // Deactivates keyboard to unregister existing listeners.
+  controller->DeactivateKeyboard(keyboard_controller);

[xiyuan, 2017/03/17 07:08:16]

This is needed now because TestSessionControllerClient fires
SessionStateChanged. Hence WmShellAura::SessionStateChanged will be called to
CreateKeyboard, which implicitly ActivateKeyboard before test body runs.

   AlwaysOnTopController* always_on_top_controller =
       controller->always_on_top_controller();
   always_on_top_controller->SetLayoutManagerForTest(base::WrapUnique(manager));