Move yet more from WmShell to Shell

ash/wm/power_button_controller.cc

Index: ash/wm/power_button_controller.cc
diff --git a/ash/wm/power_button_controller.cc b/ash/wm/power_button_controller.cc
index c8cd426cfa2f6b45266f6e46adb82bd5e81f8119..8031ac50c3483e440ef37c4c75c2a312b564220b 100644
--- a/ash/wm/power_button_controller.cc
+++ b/ash/wm/power_button_controller.cc
@@ -104,7 +104,7 @@ void PowerButtonController::OnPowerButtonEvent(
   }
 
   const SessionController* const session_controller =
-      WmShell::Get()->session_controller();
+      Shell::Get()->session_controller();
   if (has_legacy_power_button_) {
     // If power button releases won't get reported correctly because we're not
     // running on official hardware, just lock the screen or shut down
@@ -145,7 +145,7 @@ void PowerButtonController::OnLockButtonEvent(
   lock_button_down_ = down;
 
   const SessionController* const session_controller =
-      WmShell::Get()->session_controller();
+      Shell::Get()->session_controller();
   if (!session_controller->CanLockScreen() ||
       session_controller->IsScreenLocked() ||
       lock_state_controller_->LockRequested() ||