Store AppItems as pages in AppListModel.

ui/app_list/views/app_list_main_view.cc

 // Copyright 2013 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/app_list_main_view.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/callback.h"
@@ skipping 130 matching lines @@
   contents_view_->Prerender();
 }
 
 void AppListMainView::SetDragAndDropHostOfCurrentAppList(
     ApplicationDragAndDropHost* drag_and_drop_host) {
   contents_view_->SetDragAndDropHostOfCurrentAppList(drag_and_drop_host);
 }
 
 void AppListMainView::PreloadIcons(PaginationModel* pagination_model,
                                    gfx::NativeView parent) {
+  if (model_->GetNumAppPages() == 0)
+    return;
+
   ui::ScaleFactor scale_factor = ui::SCALE_FACTOR_100P;
   if (parent)
     scale_factor = ui::GetScaleFactorForNativeView(parent);
 
   float scale = ui::GetImageScale(scale_factor);
   // |pagination_model| could have -1 as the initial selected page and
   // assumes first page (i.e. index 0) will be used in this case.
-  const int selected_page = std::max(0, pagination_model->selected_page());
-
-  const int tiles_per_page = kPreferredCols * kPreferredRows;
-  const int start_model_index = selected_page * tiles_per_page;
-  const int end_model_index = std::min(
-      static_cast<int>(model_->apps()->item_count()),
-      start_model_index + tiles_per_page);
-
+  size_t selected_page = 0;
+  if (pagination_model->selected_page() > 0) {
+    selected_page = static_cast<size_t>(pagination_model->selected_page());
+    selected_page = std::min(selected_page, model_->GetNumAppPages() - 1);
+  }
   pending_icon_loaders_.clear();
-  for (int i = start_model_index; i < end_model_index; ++i) {
-    AppListItemModel* item = model_->apps()->GetItemAt(i);
+  const AppListModel::AppItems& apps =
+      model_->GetAppItemsForPage(selected_page);
+  for (size_t i = 0; i < apps.item_count(); ++i) {
+    AppListItemModel* item = model_->GetItemAt(selected_page, i);
     if (item->icon().HasRepresentation(scale))
       continue;
 
     pending_icon_loaders_.push_back(new IconLoader(this, item, scale));
   }
 }
 
 void AppListMainView::OnIconLoadingWaitTimer() {
   GetWidget()->Show();
 }
@@ skipping 60 matching lines @@
   // Resubmit the query via a posted task so that all observers for the
   // uninstall notification are notified.
   base::MessageLoop::current()->PostTask(
       FROM_HERE,
       base::Bind(&AppListMainView::QueryChanged,
                  weak_ptr_factory_.GetWeakPtr(),
                  search_box_view_));
 }
 
 }  // namespace app_list