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

ui/base/gestures/gesture_recognizer_impl.cc

Index: ui/base/gestures/gesture_recognizer_impl.cc
diff --git a/ui/base/gestures/gesture_recognizer_impl.cc b/ui/base/gestures/gesture_recognizer_impl.cc
index 78adfab9c0e6a1b0649a75ecd68f7320a29f96a1..b5c1b8d738aea1e255004e6f9b43784b102070bf 100644
--- a/ui/base/gestures/gesture_recognizer_impl.cc
+++ b/ui/base/gestures/gesture_recognizer_impl.cc
@@ -132,12 +132,13 @@ GestureConsumer* GestureRecognizerImpl::GetTargetForLocation(
     for (int j = 0; j < GestureSequence::kMaxGesturePoints; ++j) {
       if (!points[j].in_use())
         continue;
-      gfx::Point delta =
-          points[j].last_touch_position().Subtract(location);
-      int distance = delta.x() * delta.x() + delta.y() * delta.y();
-      if (!closest_point || distance < closest_distance_squared) {
+      gfx::Vector2d delta = points[j].last_touch_position() - location;
+      // Relative distance is all we need here, so LengthSquared() is
+      // appropriate, and cheaper than Length().
+      int distance_squared = delta.LengthSquared();
+      if (!closest_point || distance_squared < closest_distance_squared) {
         closest_point = &points[j];
-        closest_distance_squared = distance;
+        closest_distance_squared = distance_squared;
       }
     }
   }