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

ui/views/controls/textfield/native_textfield_views.cc

Index: ui/views/controls/textfield/native_textfield_views.cc
diff --git a/ui/views/controls/textfield/native_textfield_views.cc b/ui/views/controls/textfield/native_textfield_views.cc
index bbecc17389b53f079a02b42eeb366899a84d270e..6aaead33524e0007518d0f2f5bbe68ab98663081 100644
--- a/ui/views/controls/textfield/native_textfield_views.cc
+++ b/ui/views/controls/textfield/native_textfield_views.cc
@@ -112,7 +112,8 @@ bool NativeTextfieldViews::OnMousePressed(const ui::MouseEvent& event) {
 
 bool NativeTextfieldViews::ExceededDragThresholdFromLastClickLocation(
     const ui::MouseEvent& event) {
-  gfx::Point location_delta = event.location().Subtract(last_click_location_);
+  gfx::Vector2d location_delta =
+      event.location().DistanceFrom(last_click_location_);
   return ExceededDragThreshold(location_delta.x(), location_delta.y());
 }