Purge the App Launcher code from Mac

ui/app_list/cocoa/apps_collection_view_drag_manager.h

-// Copyright 2013 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_COCOA_APPS_COLLECTION_VIEW_DRAG_MANAGER_H_
-#define UI_APP_LIST_COCOA_APPS_COLLECTION_VIEW_DRAG_MANAGER_H_
-
-#import <Cocoa/Cocoa.h>
-#include <stddef.h>
-
-#include "base/mac/scoped_nsobject.h"
-#include "ui/app_list/app_list_export.h"
-
-@class AppsGridController;
-@class ItemDragController;
-
-// Manager for the state associated with dragging an NSCollectionViewItem in the
-// AppsGridController. It is also a factory for the NSCollectionView pages in
-// the grid, allowing items to be dragged between pages.
-APP_LIST_EXPORT
-@interface AppsCollectionViewDragManager : NSObject {
- @private
-  base::scoped_nsobject<ItemDragController> itemDragController_;
-  AppsGridController* gridController_;  // Weak. Owns us.
-
-  NSSize cellSize_;
-  size_t rows_;
-  size_t columns_;
-
-  // Index of the last known position of the item currently being dragged.
-  size_t itemDragIndex_;
-
-  // Model index of the item being dragged, or NSNotFound if nothing was hit on
-  // the last mouseDown.
-  size_t itemHitIndex_;
-
-  // Location in the window of the last mouseDown event.
-  NSPoint mouseDownLocation_;
-
-  // Whether the current mouse action has converted into an item drag.
-  BOOL dragging_;
-}
-
-- (id)initWithCellSize:(NSSize)cellSize
-                  rows:(size_t)rows
-               columns:(size_t)columns
-        gridController:(AppsGridController*)gridController;
-
-// Make an empty NSCollectionView with draggable items in the given |pageFrame|.
-- (NSCollectionView*)makePageWithFrame:(NSRect)pageFrame;
-
-- (void)cancelDrag;
-
-@end
-
-@interface AppsCollectionViewDragManager (TestingAPI)
-
-- (void)onMouseDownInPage:(NSCollectionView*)page
-                withEvent:(NSEvent*)theEvent;
-- (void)onMouseDragged:(NSEvent*)theEvent;
-- (void)onMouseUp:(NSEvent*)theEvent;
-
-@end
-
-#endif  // UI_APP_LIST_COCOA_APPS_COLLECTION_VIEW_DRAG_MANAGER_H_