Add Vector2d classes that represent offsets, instead of using Point.

ui/app_list/apps_grid_view.cc

 // Copyright (c) 2012 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.
 
 #include "ui/app_list/apps_grid_view.h"
 
 #include <algorithm>
 
 #include "ui/app_list/app_list_item_model.h"
 #include "ui/app_list/app_list_item_view.h"
@@ skipping 151 matching lines @@
     pagination_model_->SelectPage(index.page, false);
 }
 
 void AppsGridView::InitiateDrag(views::View* view,
                                 Pointer pointer,
                                 const ui::LocatedEvent& event) {
   if (drag_view_)
     return;
 
   drag_view_ = view;
-  drag_offset_ = event.location();
+  drag_offset_ = event.location().DistanceFromOrigin();
 }
 
 void AppsGridView::UpdateDrag(views::View* view,
                               Pointer pointer,
                               const ui::LocatedEvent& event) {
   if (!dragging() && drag_view_ &&
       ExceededDragThreshold(event.x() - drag_offset_.x(),
                             event.y() - drag_offset_.y())) {
     drag_pointer_ = pointer;
     // Move the view to the front so that it appears on top of other views.
@@ skipping 513 matching lines @@
 void AppsGridView::TransitionChanged() {
   // Update layout for valid page transition only since over-scroll no longer
   // animates app icons.
   const PaginationModel::Transition& transition =
       pagination_model_->transition();
   if (pagination_model_->is_valid_page(transition.target_page))
     Layout();
 }
 
 }  // namespace app_list