Attempt to re-land FocusManager removal from Aura.

ash/shell.cc

 // 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 "ash/shell.h"
 
 #include <algorithm>
 #include <string>
 
 #include "ash/accelerators/accelerator_controller.h"
@@ skipping 65 matching lines @@
 #include "ash/wm/window_properties.h"
 #include "ash/wm/window_util.h"
 #include "ash/wm/workspace_controller.h"
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/debug/leak_annotations.h"
 #include "base/debug/trace_event.h"
 #include "ui/aura/client/aura_constants.h"
 #include "ui/aura/client/user_action_client.h"
 #include "ui/aura/env.h"
-#include "ui/aura/focus_manager.h"
 #include "ui/aura/layout_manager.h"
 #include "ui/aura/root_window.h"
 #include "ui/aura/window.h"
 #include "ui/base/ui_base_switches.h"
 #include "ui/compositor/layer.h"
 #include "ui/compositor/layer_animator.h"
 #include "ui/gfx/display.h"
 #include "ui/gfx/image/image_skia.h"
 #include "ui/gfx/screen.h"
 #include "ui/gfx/size.h"
@@ skipping 879 matching lines @@
 ////////////////////////////////////////////////////////////////////////////////
 // Shell, aura::client::ActivationChangeObserver implementation:
 
 void Shell::OnWindowActivated(aura::Window* gained_active,
                               aura::Window* lost_active) {
   if (gained_active)
     target_root_window_ = gained_active->GetRootWindow();
 }
 
 }  // namespace ash