Allow pages on the OSX app launcher to be turned while dragging.

ui/app_list/cocoa/apps_collection_view_drag_manager.mm

 // 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.
 
 #import "ui/app_list/cocoa/apps_collection_view_drag_manager.h"
 
 #include "base/logging.h"
 #include "base/mac/foundation_util.h"
 #import "ui/app_list/cocoa/apps_grid_controller.h"
 #import "ui/app_list/cocoa/apps_grid_view_item.h"
@@ skipping 127 matching lines @@
   return NSNotFound;
 }
 
 - (void)initiateDrag:(NSEvent*)theEvent {
   DCHECK_LT(itemHitIndex_, [gridController_ itemCount]);
   dragging_ = YES;
 
   if (!itemDragController_) {
     itemDragController_.reset(
         [[ItemDragController alloc] initWithGridCellSize:cellSize_]);
-    [[gridController_ view] addSubview:[itemDragController_ view]];
+    [[[gridController_ view] superview] addSubview:[itemDragController_ view]];
   }
 
   [itemDragController_ initiate:[gridController_ itemAtIndex:itemHitIndex_]
               mouseDownLocation:mouseDownLocation_
                 currentLocation:[theEvent locationInWindow]
                       timestamp:[theEvent timestamp]];
 
   itemDragIndex_ = itemHitIndex_;
   [self updateDrag:theEvent];
 }
 
 - (void)updateDrag:(NSEvent*)theEvent {
   [itemDragController_ update:[theEvent locationInWindow]
                     timestamp:[theEvent timestamp]];
+  [gridController_ maybeChangePageForPoint:[theEvent locationInWindow]];
+
   size_t visiblePage = [gridController_ visiblePage];
   size_t itemIndexOver = [self itemIndexForPage:visiblePage
                                    hitWithEvent:theEvent];
   DCHECK_NE(0u, [gridController_ itemCount]);
   if (itemIndexOver == NSNotFound) {
     if (visiblePage != [gridController_ pageCount] - 1)
       return;
 
     // If nothing was hit, but the last page is shown, move to the end.
     itemIndexOver = [gridController_ itemCount] - 1;
@@ skipping 15 matching lines @@
 
   [gridController_ moveItemInView:itemDragIndex_
                       toItemIndex:itemHitIndex_];
   itemDragIndex_ = itemHitIndex_;
   [self completeDrag];
   itemHitIndex_ = NSNotFound;  // Ignore future mouse events for this drag.
 }
 
 - (void)completeDrag {
   DCHECK_GE(itemDragIndex_, 0u);
+  [gridController_ cancelScrollTimer];
   AppsGridViewItem* item = [gridController_ itemAtIndex:itemDragIndex_];
 
   // The item could still be animating in the NSCollectionView, so ask it where
   // it would place the item.
   NSCollectionView* pageView = base::mac::ObjCCastStrict<NSCollectionView>(
       [[item view] superview]);
   size_t indexInPage = itemDragIndex_ % (rows_ * columns_);
-  NSPoint targetOrigin = [[gridController_ view]
+  NSPoint targetOrigin = [[[itemDragController_ view] superview]
       convertPoint:[pageView frameForItemAtIndex:indexInPage].origin
           fromView:pageView];
 
   [itemDragController_ complete:item
                    targetOrigin:targetOrigin];
   [gridController_ moveItemWithIndex:itemHitIndex_
                         toModelIndex:itemDragIndex_];
 
   dragging_ = NO;
 }
@@ skipping 15 matching lines @@
 
 - (void)mouseUp:(NSEvent*)theEvent {
   [factory_ onMouseUp:theEvent];
 }
 
 - (BOOL)acceptsFirstResponder {
   return NO;
 }
 
 @end