Fix weird movement when folder is created or distroyed

When the folder is created, the folder item view's origin is initiated
with (0, 0). So after dragging the folder item view will be animated to
where it is supposed to be, which cause the weird movement.

The same thing happens when the last item is moved outside the folder.

Changes:
Use the original view's bounds to set the newly created view's bounds
before the deletion of the original view.

BUG=819664

Change-Id: Id0066b27a0bd30f04e5b62c6b782178fbf84d48c
Reviewed-on: https://chromium-review.googlesource.com/953204Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: Weidong Guo <weidongg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#541620}

ui/app_list/views/apps_grid_view.cc

@@ -2085,10 +2085,14 @@ bool AppsGridView::ReparentItemToAnotherFolder(AppListItemView* item_view,
     const std::string& new_folder_id = reparent_item->folder_id();
     size_t new_folder_index;
     if (item_list_->FindItemIndex(new_folder_id, &new_folder_index)) {
+      // Save the target view's bounds before deletion, which will be used as
+      // new folder view's bounds.
+      gfx::Rect target_rect = target_view->bounds();
       int target_view_index = view_model_.GetIndexOfView(target_view);
       DeleteItemViewAtIndex(target_view_index);
       AppListItemView* new_folder_view =
           CreateViewForItemAtIndex(new_folder_index);
+      new_folder_view->SetBoundsRect(target_rect);
       view_model_.Add(new_folder_view, target_view_index);
       AddChildViewAt(new_folder_view,
                      GetAppListItemViewIndexOffset() + new_folder_index);
@@ -2125,6 +2129,9 @@ void AppsGridView::RemoveLastItemFromReparentItemFolderIfNecessary(
   if (!source_folder || source_folder->ChildItemCount() != 1u)
     return;
 
+  // Save the folder item view's bounds before deletion, which will be used as
+  // last item view's bounds.
+  gfx::Rect folder_rect = activated_folder_item_view()->bounds();
   // Delete view associated with the folder item to be removed.
   DeleteItemViewAtIndex(
       view_model_.GetIndexOfView(activated_folder_item_view()));
@@ -2141,6 +2148,7 @@ void AppsGridView::RemoveLastItemFromReparentItemFolderIfNecessary(
     return;
   }
   AppListItemView* last_item_view = CreateViewForItemAtIndex(last_item_index);
+  last_item_view->SetBoundsRect(folder_rect);
   view_model_.Add(last_item_view, last_item_index);
   AddChildViewAt(last_item_view,
                  GetAppListItemViewIndexOffset() + last_item_index);