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

ui/base/gtk/gtk_screen_util.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/base/gtk/gtk_screen_util.h"
 
 #include "base/logging.h"
 
 namespace ui {
 
 bool IsScreenComposited() {
   GdkScreen* screen = gdk_screen_get_default();
   return gdk_screen_is_composited(screen) == TRUE;
 }
 
 gfx::Point ScreenPoint(GtkWidget* widget) {
   int x, y;
   gdk_display_get_pointer(gtk_widget_get_display(widget), NULL, &x, &y,
                           NULL);
   return gfx::Point(x, y);
 }
 
 gfx::Point ClientPoint(GtkWidget* widget) {
   int x, y;
   gtk_widget_get_pointer(widget, &x, &y);
   return gfx::Point(x, y);
 }
 
-gfx::Point GetWidgetScreenPosition(GtkWidget* widget) {
+gfx::Vector2d GetWidgetScreenOffset(GtkWidget* widget) {
   GdkWindow* window = gtk_widget_get_window(widget);
 
   if (!window) {
     NOTREACHED() << "Must only be called on realized widgets.";
-    return gfx::Point(0, 0);
+    return gfx::Vector2d(0, 0);
   }
 
   gint x, y;
   gdk_window_get_origin(window, &x, &y);
 
   if (!gtk_widget_get_has_window(widget)) {
     GtkAllocation allocation;
     gtk_widget_get_allocation(widget, &allocation);
     x += allocation.x;
     y += allocation.y;
   }
 
-  return gfx::Point(x, y);
+  return gfx::Vector2d(x, y);
 }
 
 gfx::Rect GetWidgetScreenBounds(GtkWidget* widget) {
-  gfx::Point position = GetWidgetScreenPosition(widget);
-
   GtkAllocation allocation;
   gtk_widget_get_allocation(widget, &allocation);
 
-  return gfx::Rect(position.x(), position.y(),
-                   allocation.width, allocation.height);
+  return gfx::Rect(PointAtOffsetFromOrigin(GetWidgetScreenOffset(widget)),
+                   gfx::Size(allocation.width, allocation.height));
 }
 
 }  // namespace ui