Moves maintaining ShellObservers back to Shell

ash/virtual_keyboard_controller.cc

Index: ash/virtual_keyboard_controller.cc
diff --git a/ash/virtual_keyboard_controller.cc b/ash/virtual_keyboard_controller.cc
index b483df6e5c4475c943f439443e136acd321e8f51..2616875b9d95a1b8d32355d0b6d437dcfbe54d30 100644
--- a/ash/virtual_keyboard_controller.cc
+++ b/ash/virtual_keyboard_controller.cc
@@ -72,13 +72,13 @@ VirtualKeyboardController::VirtualKeyboardController()
       has_internal_keyboard_(false),
       has_touchscreen_(false),
       ignore_external_keyboard_(false) {
-  WmShell::Get()->AddShellObserver(this);
+  Shell::GetInstance()->AddShellObserver(this);
   ui::InputDeviceManager::GetInstance()->AddObserver(this);
   UpdateDevices();
 }
 
 VirtualKeyboardController::~VirtualKeyboardController() {
-  WmShell::Get()->RemoveShellObserver(this);
+  Shell::GetInstance()->RemoveShellObserver(this);
   ui::InputDeviceManager::GetInstance()->RemoveObserver(this);
 }