Add a skeleton Start Page to the experimental app list.

ui/app_list/views/contents_view.h

Index: ui/app_list/views/contents_view.h
diff --git a/ui/app_list/views/contents_view.h b/ui/app_list/views/contents_view.h
index eb2ec6def49adf394a4e3b631d4014cc05660ad2..07764beaa6e1c22794c1fe8432b09eb12793033b 100644
--- a/ui/app_list/views/contents_view.h
+++ b/ui/app_list/views/contents_view.h
@@ -29,6 +29,7 @@ class AppListModel;
 class AppListViewDelegate;
 class AppsContainerView;
 class PaginationModel;
+class StartPageView;
 
 // A view to manage sub views under the search box (apps grid view + page
 // switcher and search results). The two sets of sub views are mutually
@@ -36,7 +37,7 @@ class PaginationModel;
 // and animates the transition between show states.
 class ContentsView : public views::View {
  public:
-  enum ShowState { SHOW_APPS, SHOW_SEARCH_RESULTS, };
+  enum ShowState { SHOW_APPS, SHOW_SEARCH_RESULTS, SHOW_START_PAGE, };
 
   ContentsView(AppListMainView* app_list_main_view,
                PaginationModel* pagination_model,
@@ -69,6 +70,8 @@ class ContentsView : public views::View {
   virtual bool OnMouseWheel(const ui::MouseWheelEvent& event) OVERRIDE;
 
  private:
+  AppListMainView* GetMainView();

[xiyuan, 2014/03/14 17:00:54]

Seems not used. And casting parent is not safe, if we need this, I would prefer
to keep a copy of AppListMainView passed in ctor and use that.

[calamity, 2014/05/07 06:11:52]

Done.

+
   // Invoked when show state is changed.
   void ShowStateChanged();