Implement app list folder management page UI.

ui/app_list/views/app_list_main_view.cc

Index: ui/app_list/views/app_list_main_view.cc
diff --git a/ui/app_list/views/app_list_main_view.cc b/ui/app_list/views/app_list_main_view.cc
index 792c5bd8355bdfa59d059de8d239026b526b92cb..b4efa6cbe2d46ab1062e0d461dfc1847a42d31fc 100644
--- a/ui/app_list/views/app_list_main_view.cc
+++ b/ui/app_list/views/app_list_main_view.cc
@@ -12,6 +12,7 @@
 #include "base/message_loop/message_loop.h"
 #include "base/strings/string_util.h"
 #include "ui/app_list/app_list_constants.h"
+#include "ui/app_list/app_list_folder_item.h"
 #include "ui/app_list/app_list_item_model.h"
 #include "ui/app_list/app_list_model.h"
 #include "ui/app_list/app_list_view_delegate.h"
@@ -190,7 +191,10 @@ void AppListMainView::OnItemIconLoaded(IconLoader* loader) {
 }
 
 void AppListMainView::ActivateApp(AppListItemModel* item, int event_flags) {
-  item->Activate(event_flags);
+  if (item->GetAppType() == AppListFolderItem::kAppType)
+    contents_view_->ShowFolderContent(static_cast<AppListFolderItem*>(item));

[xiyuan, 2013/10/17 23:50:30]

Per discussion, put to TODO here to achieve this via model (or delegate).

[jennyz, 2013/10/18 22:09:02]

Done.

+  else
+    item->Activate(event_flags);
 }
 
 void AppListMainView::GetShortcutPathForApp(