Draggable peeking/fullscreen launcher with transparent background.

ui/app_list/views/start_page_view.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_APP_LIST_VIEWS_START_PAGE_VIEW_H_
 #define UI_APP_LIST_VIEWS_START_PAGE_VIEW_H_
 
 #include <stddef.h>
 
 #include <vector>
 
 #include "base/macros.h"
 #include "ui/app_list/app_list_export.h"
 #include "ui/app_list/views/app_list_page.h"
 
 namespace app_list {
 
 class AppListMainView;
+class AppListView;
 class AppListViewDelegate;
 class CustomLauncherPageBackgroundView;
 class SearchResultTileItemView;
 class TileItemView;
 
 // The start page for the app list.
 class APP_LIST_EXPORT StartPageView : public AppListPage {
  public:
   StartPageView(AppListMainView* app_list_main_view,
-                AppListViewDelegate* view_delegate);
+                AppListViewDelegate* view_delegate,
+                AppListView* app_list_view);
   ~StartPageView() override;
 
   void Reset();
 
   void UpdateForTesting();
 
   views::View* instant_container() const { return instant_container_; }
   const std::vector<SearchResultTileItemView*>& tile_views() const;
   TileItemView* all_apps_button() const;
 
   // Overridden from AppListPage:
   gfx::Rect GetPageBoundsForState(AppListModel::State state) const override;
   gfx::Rect GetSearchBoxBounds() const override;
   void OnShown() override;
 
   // Overridden from views::View:
   void Layout() override;
   bool OnKeyPressed(const ui::KeyEvent& event) override;
 
   bool OnMousePressed(const ui::MouseEvent& event) override;
   bool OnMouseWheel(const ui::MouseWheelEvent& event) override;
   void OnGestureEvent(ui::GestureEvent* event) override;
   void OnScrollEvent(ui::ScrollEvent* event) override;
 
-
  private:
   class StartPageTilesContainer;
 
   void InitInstantContainer();
+
   void MaybeOpenCustomLauncherPage();
 
   void SetCustomLauncherPageSelected(bool selected);
 
   TileItemView* GetTileItemView(size_t index);
 
   // The parent view of ContentsView which is the parent of this view.
   AppListMainView* app_list_main_view_;
 
   AppListViewDelegate* view_delegate_;  // Owned by AppListView.
 
   // An invisible placeholder view which fills the space for the search box view
   // in a box layout. The search box view itself is a child of the AppListView
   // (because it is visible on many different pages).
   views::View* search_box_spacer_view_;  // Owned by views hierarchy.
 
   views::View* instant_container_;  // Owned by views hierarchy.
   CustomLauncherPageBackgroundView*
       custom_launcher_page_background_;       // Owned by view hierarchy.
   StartPageTilesContainer* tiles_container_;  // Owned by views hierarchy.
 
   DISALLOW_COPY_AND_ASSIGN(StartPageView);
 };
 
 }  // namespace app_list
 
 #endif  // UI_APP_LIST_VIEWS_START_PAGE_VIEW_H_