Remove docked windows entirely in M59.

ash/common/wm/window_state_observer.h

Index: ash/common/wm/window_state_observer.h
diff --git a/ash/common/wm/window_state_observer.h b/ash/common/wm/window_state_observer.h
index 7bfec4e1ad9346bf808f261020c3fdf95e93338d..867e46ef3356c59f98c1b87950d69589f34d5c55 100644
--- a/ash/common/wm/window_state_observer.h
+++ b/ash/common/wm/window_state_observer.h
@@ -25,7 +25,6 @@ class ASH_EXPORT WindowStateObserver {
   // the window's bounds has been updated for the new type.
   // This is used to update the shell state such as work area so
   // that the window can use the correct environment to update its bounds.
-  // TODO(oshima): Remove this once docked windows has its own state.
   virtual void OnPreWindowStateTypeChange(WindowState* window_state,
                                           WindowStateType old_type) {}