Add a skeleton Start Page to the experimental app list.

ui/app_list/views/apps_grid_view.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/app_list/views/apps_grid_view.h"
 
 #include <algorithm>
 #include <set>
 #include <string>
 
@@ skipping 322 matching lines @@
       bounds_animator_(this),
       is_root_level_(true),
       activated_item_view_(NULL),
       dragging_for_reparent_item_(false) {
   SetPaintToLayer(true);
   SetFillsBoundsOpaquely(false);
 
   pagination_model_->AddObserver(this);
   AddChildView(page_switcher_view_);
 
-  if (start_page_contents) {
+  if (start_page_contents && app_list::switches::IsStartPageWebUIEnabled()) {
     start_page_view_ =
         new views::WebView(start_page_contents->GetBrowserContext());
     start_page_view_->SetWebContents(start_page_contents);
     AddChildView(start_page_view_);
   }
 }
 
 AppsGridView::~AppsGridView() {
   // Coming here |drag_view_| should already be canceled since otherwise the
   // drag would disappear after the app list got animated away and closed,
@@ skipping 1727 matching lines @@
 void AppsGridView::SetAsFolderDroppingTarget(const Index& target_index,
                                              bool is_target_folder) {
   AppListItemView* target_view =
       static_cast<AppListItemView*>(
           GetViewAtSlotOnCurrentPage(target_index.slot));
   if (target_view)
     target_view->SetAsAttemptedFolderTarget(is_target_folder);
 }
 
 }  // namespace app_list