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

chrome/browser/ui/gtk/tabs/tab_renderer_gtk.cc

Index: chrome/browser/ui/gtk/tabs/tab_renderer_gtk.cc
diff --git a/chrome/browser/ui/gtk/tabs/tab_renderer_gtk.cc b/chrome/browser/ui/gtk/tabs/tab_renderer_gtk.cc
index a785d9d3d505a8b8fd10305b0d277614afc7afc3..108e794ef7be64875c66f32f2139cf8851ddac9b 100644
--- a/chrome/browser/ui/gtk/tabs/tab_renderer_gtk.cc
+++ b/chrome/browser/ui/gtk/tabs/tab_renderer_gtk.cc
@@ -93,15 +93,9 @@ const int kCloseButtonHorzFuzz = 4;
 // Gets the bounds of |widget| relative to |parent|.
 gfx::Rect GetWidgetBoundsRelativeToParent(GtkWidget* parent,
                                           GtkWidget* widget) {
-  gfx::Point parent_pos = ui::GetWidgetScreenPosition(parent);
-  gfx::Point widget_pos = ui::GetWidgetScreenPosition(widget);
-
-  GtkAllocation allocation;
-  gtk_widget_get_allocation(widget, &allocation);
-
-  return gfx::Rect(widget_pos.x() - parent_pos.x(),
-                   widget_pos.y() - parent_pos.y(),
-                   allocation.width, allocation.height);
+  gfx::Rect bounds = ui::GetWidgetScreenBounds(widget);
+  bounds.Offset(-ui::GetWidgetScreenOffset(parent));
+  return bounds;
 }
 
 }  // namespace