Change ContentsView::SetActivePage to use States rather than indexes.

ui/app_list/views/contents_view.cc

Index: ui/app_list/views/contents_view.cc
diff --git a/ui/app_list/views/contents_view.cc b/ui/app_list/views/contents_view.cc
index 11bbd3f04ebd389087ce4e381d94ea1b1baff881..024466e77a85c33d6a0629ce9aef91047af9897b 100644
--- a/ui/app_list/views/contents_view.cc
+++ b/ui/app_list/views/contents_view.cc
@@ -131,15 +131,15 @@ void ContentsView::SetDragAndDropHostOfCurrentAppList(
   apps_container_view_->SetDragAndDropHostOfCurrentAppList(drag_and_drop_host);
 }
 
-void ContentsView::SetActivePage(int page_index) {
-  SetActivePage(page_index, true);
+void ContentsView::SetActivePage(AppListModel::State state) {
+  SetActivePage(state, true);
 }
 
-void ContentsView::SetActivePage(int page_index, bool animate) {
-  if (GetActivePageIndex() == page_index)
+void ContentsView::SetActivePage(AppListModel::State state, bool animate) {
+  if (IsStateActive(state))
     return;
 
-  SetActivePageInternal(page_index, false, animate);
+  SetActivePageInternal(GetPageIndexForState(state), false, animate);
 }
 
 int ContentsView::GetActivePageIndex() const {
@@ -432,13 +432,13 @@ bool ContentsView::Back() {
       if (app_list_main_view_->model()->PopCustomLauncherPageSubpage())
         app_list_main_view_->view_delegate()->CustomLauncherPagePopSubpage();
       else
-        SetActivePage(GetPageIndexForState(AppListModel::STATE_START));
+        SetActivePage(AppListModel::STATE_START);
       break;
     case AppListModel::STATE_APPS:
       if (apps_container_view_->IsInFolderView())
         apps_container_view_->app_list_folder_view()->CloseFolderPage();
       else
-        SetActivePage(GetPageIndexForState(AppListModel::STATE_START));
+        SetActivePage(AppListModel::STATE_START);
       break;
     case AppListModel::STATE_SEARCH_RESULTS:
       GetSearchBoxView()->ClearSearch();