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..c85f0ef57c4ae4dae1b8943af5e9758d65d3a311 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"
@@ -33,13 +35,16 @@ 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 {
+  // 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 {
     SHOW_APPS,

[benwells, 2014/06/06 06:12:29]

Nit: should be NAMED_PAGE_APPS, etc.

[Matt Giuca, 2014/06/10 04:01:19]

Done.

[benwells, 2014/06/10 08:06:42]

There seems to be a new style for enums; as your enum is NamedPage these should
be NAMED_PAGE_FOO. (see https://codereview.chromium.org/307873002/ which is the
first time I' saw it).

[Matt Giuca, 2014/06/10 08:45:08]

OK, renamed again.

     SHOW_SEARCH_RESULTS,
     SHOW_START_PAGE,
@@ -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() const { return active_page_; }

[benwells, 2014/06/06 06:12:29]

Nit: active_page -> active_page_index

[Matt Giuca, 2014/06/10 04:01:19]

Done.

+
+  // 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 +90,20 @@ 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 child of the ContentsView. Also adds it to the view model,
+  // having no named page associated with it.
+  void AddLauncherPage(views::View* view);

[benwells, 2014/06/06 06:12:29]

Should these mention that it is added next in the list of views?

[Matt Giuca, 2014/06/10 04:01:19]

Not sure what you mean -- the buttons along the bottom? It doesn't actually do
that yet (see TODO in contents_switcher_view), so I'll hold off on saying that
until it is the truth.

[benwells, 2014/06/10 08:06:42]

I mean there is an ordering to the pages, and when you call AddLauncherPage you
add the page to the end of the order.

[Matt Giuca, 2014/06/10 08:45:08]

Done.

+
+  // Adds |view| as a child of the ContentsView. Also adds it to the view model,
+  // associating it with |named_page|.
+  void AddLauncherPage(views::View* view, NamedPage named_page);
+
   // Gets the PaginationModel owned by the AppsGridView.
   PaginationModel* GetAppsPaginationModel();
 
@@ -91,7 +111,8 @@ 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 +122,8 @@ 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);