Attempt to re-land FocusManager removal from Aura.

ui/views/corewm/focus_controller.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 "ui/views/corewm/focus_controller.h"
 
 #include "base/auto_reset.h"
 #include "ui/aura/client/activation_change_observer.h"
 #include "ui/aura/client/aura_constants.h"
 #include "ui/aura/client/capture_client.h"
@@ skipping 161 matching lines @@
     return;
   if (!active_window_->Contains(window))
     return;
   SetFocusedWindow(window);
 }
 
 aura::Window* FocusController::GetFocusedWindow() {
   return focused_window_;
 }
 
-void FocusController::OnWindowHiddenInRootWindow(
-    aura::Window* window,
-    aura::RootWindow* root_window,
-    bool destroyed) {
-  //NOTREACHED();
-  // This method is only for compat with aura::FocusManager. It should not be
-  // needed in the new FocusController.
-}
-
 ////////////////////////////////////////////////////////////////////////////////
 // FocusController, ui::EventHandler implementation:
 void FocusController::OnKeyEvent(ui::KeyEvent* event) {
 }
 
 void FocusController::OnMouseEvent(ui::MouseEvent* event) {
   if (event->type() == ui::ET_MOUSE_PRESSED)
     WindowFocusedFromInputEvent(static_cast<aura::Window*>(event->target()));
 }
 
@@ skipping 151 matching lines @@
 void FocusController::WindowFocusedFromInputEvent(aura::Window* window) {
   // Only focus |window| if it or any of its parents can be focused. Otherwise
   // FocusWindow() will focus the topmost window, which may not be the
   // currently focused one.
   if (rules_->CanFocusWindow(GetToplevelWindow(window)))
     FocusWindow(window);
 }
 
 }  // namespace corewm
 }  // namespace views