Change the launcher to use AccessiblePaneView, and make the buttons focusable

ash/launcher/app_launcher_button.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/launcher/app_launcher_button.h"
 
 #include <algorithm>
 
 #include "ash/launcher/launcher_button_host.h"
 #include "ui/gfx/canvas_skia.h"
 
 namespace ash {
 
 namespace internal {
 
 const int kImageSize = 32;
 
 AppLauncherButton::AppLauncherButton(views::ButtonListener* listener,
                                      LauncherButtonHost* host)
     : views::ImageButton(listener),
       host_(host) {
   SetImageAlignment(views::ImageButton::ALIGN_CENTER,
                     views::ImageButton::ALIGN_MIDDLE);
+  set_focusable(true);
 }
 
 AppLauncherButton::~AppLauncherButton() {
 }
 
 void AppLauncherButton::SetAppImage(const SkBitmap& image) {
   if (image.empty()) {
     // TODO: need an empty image.
     SetImage(BS_NORMAL, &image);
     return;
@@ skipping 41 matching lines @@
   return true;
 }
 
 void AppLauncherButton::OnMouseExited(const views::MouseEvent& event) {
   ImageButton::OnMouseExited(event);
   host_->MouseExitedButton(this);
 }
 
 }  // namespace internal
 }  // namespace ash