ash: Use SessionController instead of SessionStateDelegate

ash/system/chromeos/power/tablet_power_button_controller_unittest.cc

Index: ash/system/chromeos/power/tablet_power_button_controller_unittest.cc
diff --git a/ash/system/chromeos/power/tablet_power_button_controller_unittest.cc b/ash/system/chromeos/power/tablet_power_button_controller_unittest.cc
index 3f06a501e28d74f6e0b6cb5b3f11c513e3ed9c0a..40db38feafcfa67b7d262e5f70c5c5a0a944cefd 100644
--- a/ash/system/chromeos/power/tablet_power_button_controller_unittest.cc
+++ b/ash/system/chromeos/power/tablet_power_button_controller_unittest.cc
@@ -7,7 +7,8 @@
 #include <memory>
 
 #include "ash/common/ash_switches.h"
-#include "ash/common/session/session_state_delegate.h"
+#include "ash/common/session/session_controller.h"
+#include "ash/common/test/test_session_controller_client.h"
 #include "ash/common/wm/maximize_mode/maximize_mode_controller.h"
 #include "ash/common/wm_shell.h"
 #include "ash/shell.h"
@@ -93,7 +94,7 @@ class TabletPowerButtonControllerTest : public AshTestBase {
 
   void UnlockScreen() {
     lock_state_controller_->OnLockStateChanged(false);
-    WmShell::Get()->GetSessionStateDelegate()->UnlockScreen();
+    GetSessionControllerClient()->UnlockScreen();
   }
 
   void Initialize(LoginStatus status) {
@@ -108,7 +109,10 @@ class TabletPowerButtonControllerTest : public AshTestBase {
   }
 
   bool GetLockedState() {
-    return WmShell::Get()->GetSessionStateDelegate()->IsScreenLocked();
+    // LockScreen is an async mojo call. Spin message loop to ensure it is
+    // delivered.
+    RunAllPendingInMessageLoop();

[James Cook, 2017/03/17 17:14:36]

This might be a good candidate for SessionController::FlushMojoForTesting()

[xiyuan, 2017/03/17 22:52:03]

Done.

+    return WmShell::Get()->session_controller()->IsScreenLocked();
   }
 
   bool GetBacklightsForcedOff() WARN_UNUSED_RESULT {