Refactor app list ContentsView to use page indices, not show states.

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 e7df7bc0ccbf4b75207aaa04856e5a12c7561ebb..0a7bfc5cca48011abd644264cb2801597a2fb4af 100644
--- a/ui/app_list/views/contents_view.h
+++ b/ui/app_list/views/contents_view.h
@@ -5,6 +5,8 @@
 #ifndef UI_APP_LIST_VIEWS_CONTENTS_VIEW_H_
 #define UI_APP_LIST_VIEWS_CONTENTS_VIEW_H_
 
+#include <map>
+
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
@@ -33,16 +35,19 @@ class PaginationModel;
 class SearchResultListView;
 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
-// exclusive. ContentsView manages a show state to choose one set to show
-// and animates the transition between show states.
+// A view to manage launcher pages within the Launcher (eg. start page, apps
+// grid view, search results). There can be any number of launcher pages, only
+// one of which can be active at a given time. ContentsView provides the user
+// interface for switching between launcher pages, and animates the transition
+// between them.
 class APP_LIST_EXPORT ContentsView : public views::View {
  public:
-  enum ShowState {
-    SHOW_APPS,
-    SHOW_SEARCH_RESULTS,
-    SHOW_START_PAGE,
+  // Values of this enum denote special launcher pages that require hard-coding.
+  // Launcher pages are not required to have a NamedPage enum value.
+  enum NamedPage {
+    NAMED_PAGE_APPS,
+    NAMED_PAGE_SEARCH_RESULTS,
+    NAMED_PAGE_START,
   };
 
   ContentsView(AppListMainView* app_list_main_view,
@@ -61,16 +66,23 @@ class APP_LIST_EXPORT ContentsView : public views::View {
   void ShowSearchResults(bool show);
   void ShowFolderContent(AppListFolderItem* folder);
 
-  // Sets show state and animates the subviews to match the show state.
-  void SetShowState(ShowState show_state);
+  // Sets the active launcher page and animates the pages into place.
+  void SetActivePage(int page_index);
+
+  // The index of the currently active launcher page.
+  int active_page_index() const { return active_page_; }
+
+  // True if |named_page| is the current active laucher page.
+  bool IsNamedPageActive(NamedPage named_page) const;
+
+  // Gets the index of a launcher page in |view_model_|, by NamedPage.
+  int GetPageIndexForNamedPage(NamedPage named_page) const;
 
   void Prerender();
 
   AppsContainerView* apps_container_view() { return apps_container_view_; }
   StartPageView* start_page_view() { return start_page_view_; }
 
-  ShowState show_state() const { return show_state_; }
-
   // Overridden from views::View:
   virtual gfx::Size GetPreferredSize() const OVERRIDE;
   virtual void Layout() OVERRIDE;
@@ -78,12 +90,22 @@ class APP_LIST_EXPORT ContentsView : public views::View {
   virtual bool OnMouseWheel(const ui::MouseWheelEvent& event) OVERRIDE;
 
  private:
-  // Invoked when show state is changed.
-  void ShowStateChanged();
+  // Invoked when active view is changed.
+  void ActivePageChanged();
 
   void CalculateIdealBounds();
   void AnimateToIdealBounds();
 
+  // Adds |view| as a new page to the end of the list of launcher pages. The
+  // view is inserted as a child of the ContentsView. There is no name
+  // associated with the page. Returns the index of the new page.
+  int AddLauncherPage(views::View* view);
+
+  // Adds |view| as a new page to the end of the list of launcher pages. The
+  // view is inserted as a child of the ContentsView. The page is associated
+  // with the name |named_page|. Returns the index of the new page.
+  int AddLauncherPage(views::View* view, NamedPage named_page);
+
   // Gets the PaginationModel owned by the AppsGridView.
   PaginationModel* GetAppsPaginationModel();
 
@@ -91,7 +113,8 @@ class APP_LIST_EXPORT ContentsView : public views::View {
   virtual void OnGestureEvent(ui::GestureEvent* event) OVERRIDE;
   virtual void OnScrollEvent(ui::ScrollEvent* event) OVERRIDE;
 
-  ShowState show_state_;
+  // Index into |view_model_| of the currently active page.
+  int active_page_;
 
   // Special sub views of the ContentsView. All owned by the views hierarchy.
   AppsContainerView* apps_container_view_;
@@ -101,6 +124,8 @@ class APP_LIST_EXPORT ContentsView : public views::View {
   AppListMainView* app_list_main_view_;     // Parent view, owns this.
 
   scoped_ptr<views::ViewModel> view_model_;
+  // Maps NamedPage onto |view_model_| indices.
+  std::map<NamedPage, int> named_page_to_view_;
   scoped_ptr<views::BoundsAnimator> bounds_animator_;
 
   DISALLOW_COPY_AND_ASSIGN(ContentsView);