Makes ash/wm/common a library

ash/wm/common/wm_lookup.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "ash/wm/common/shelf/wm_shelf_util.h"
+#include "ash/wm/common/wm_lookup.h"
 
 namespace ash {
 namespace wm {
 
-bool IsHorizontalAlignment(wm::ShelfAlignment alignment) {
-  return alignment == wm::SHELF_ALIGNMENT_BOTTOM ||
-         alignment == wm::SHELF_ALIGNMENT_BOTTOM_LOCKED;
+// static
+WmLookup* WmLookup::instance_ = nullptr;
+
+// static
+void WmLookup::Set(WmLookup* lookup) {
+  instance_ = lookup;
+}
+
+// static
+WmLookup* WmLookup::Get() {
+  return instance_;
 }
 
 }  // namespace wm
 }  // namespace ash