It is time.

ui/aura/window_tracker.cc

Index: ui/aura/window_tracker.cc
diff --git a/ui/aura/window_tracker.cc b/ui/aura/window_tracker.cc
deleted file mode 100644
index 9653e5fcf9ea57dc2b147e0e2f34b6d041cdef9b..0000000000000000000000000000000000000000
--- a/ui/aura/window_tracker.cc
+++ /dev/null
@@ -1,43 +0,0 @@
-// Copyright (c) 2012 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 "ui/aura/window_tracker.h"
-
-#include "ui/aura/window.h"
-
-namespace aura {
-
-WindowTracker::WindowTracker() {
-}
-
-WindowTracker::~WindowTracker() {
-  for (Windows::iterator i = windows_.begin(); i != windows_.end(); ++i)
-    (*i)->RemoveObserver(this);
-}
-
-void WindowTracker::Add(Window* window) {
-  if (windows_.count(window))
-    return;
-
-  window->AddObserver(this);
-  windows_.insert(window);
-}
-
-void WindowTracker::Remove(Window* window) {
-  if (windows_.count(window)) {
-    windows_.erase(window);
-    window->RemoveObserver(this);
-  }
-}
-
-bool WindowTracker::Contains(Window* window) {
-  return windows_.count(window) > 0;
-}
-
-void WindowTracker::OnWindowDestroying(Window* window) {
-  DCHECK_GT(windows_.count(window), 0u);
-  Remove(window);
-}
-
-}  // namespace aura