Makes ash/wm/common a library

ash/wm/common/wm_lookup.cc

Index: ash/wm/common/wm_lookup.cc
diff --git a/ash/wm/common/shelf/wm_shelf_util.cc b/ash/wm/common/wm_lookup.cc
similarity index 52%
copy from ash/wm/common/shelf/wm_shelf_util.cc
copy to ash/wm/common/wm_lookup.cc
index 5133feb7600ddba33547cf43974d2ab5edcd4bc6..91f9dc255edeb0707f80058930dbc0f5b7f3d732 100644
--- a/ash/wm/common/shelf/wm_shelf_util.cc
+++ b/ash/wm/common/wm_lookup.cc
@@ -2,14 +2,22 @@
 // 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