mash: Remove WmRootWindowControllerObserver.

ash/common/wm_root_window_controller.cc

Index: ash/common/wm_root_window_controller.cc
diff --git a/ash/common/wm_root_window_controller.cc b/ash/common/wm_root_window_controller.cc
index da636051e892d2431b4fc68ec1cb44f9739b6ff4..f4875927196eb4f14d93dfe2371a6c8ef0c74a51 100644
--- a/ash/common/wm_root_window_controller.cc
+++ b/ash/common/wm_root_window_controller.cc
@@ -38,16 +38,6 @@ wm::WorkspaceWindowState WmRootWindowController::GetWorkspaceWindowState() {
                                : wm::WORKSPACE_WINDOW_STATE_DEFAULT;
 }
 
-void WmRootWindowController::AddObserver(
-    WmRootWindowControllerObserver* observer) {
-  observers_.AddObserver(observer);
-}
-
-void WmRootWindowController::RemoveObserver(
-    WmRootWindowControllerObserver* observer) {
-  observers_.RemoveObserver(observer);
-}
-
 void WmRootWindowController::CreateContainers() {
   // These containers are just used by PowerButtonController to animate groups
   // of containers simultaneously without messing up the current transformations