app_list: Touch scroll and animation improvement.

ui/app_list/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/apps_grid_view.h"
 
 #include <algorithm>
 
 #include "ui/app_list/app_list_item_view.h"
 #include "ui/app_list/pagination_model.h"
@@ skipping 257 matching lines @@
   pagination_model_->SetTotalPages(
       (child_count() - 1) / tiles_per_page() + 1);
 }
 
 AppListItemView* AppsGridView::CreateViewForItemAtIndex(size_t index) {
   DCHECK_LT(index, model_->item_count());
   AppListItemView* item = new AppListItemView(this,
                                               model_->GetItemAt(index),
                                               listener_);
   item->SetIconSize(icon_size_);
+  item->SetPaintToLayer(true);
+  item->SetFillsBoundsOpaquely(false);
   return item;
 }
 
 AppListItemView* AppsGridView::GetItemViewAtIndex(int index) {
   return static_cast<AppListItemView*>(child_at(index));
 }
 
 void AppsGridView::SetSelectedItemByIndex(int index) {
   if (selected_item_index_ == index)
     return;
@@ skipping 43 matching lines @@
 
 void AppsGridView::SelectedPageChanged(int old_selected, int new_selected) {
   Layout();
 }
 
 void AppsGridView::TransitionChanged() {
   Layout();
 }
 
 }  // namespace app_list