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

ash/display/multi_display_manager.cc

Index: ash/display/multi_display_manager.cc
diff --git a/ash/display/multi_display_manager.cc b/ash/display/multi_display_manager.cc
index d93321b3e1f26549895bc0f222aa3048ed403eb4..a81bf04069beb902a714eda0cf0267db073ad54e 100644
--- a/ash/display/multi_display_manager.cc
+++ b/ash/display/multi_display_manager.cc
@@ -523,11 +523,10 @@ void MultiDisplayManager::EnsurePointerInDisplays() {
       break;
     }
     gfx::Point center = display_bounds.CenterPoint();
-    gfx::Point diff = center.Subtract(location_in_screen);
     // Use the distance from the center of the dislay. This is not
     // exactly "closest" display, but good enough to pick one
     // appropriate (and there are at most two displays).
-    int64 distance = diff.x() * diff.x() + diff.y() * diff.y();
+    int64 distance = (center - location_in_screen).LengthSquared();

[Peter Kasting, 2012/10/29 23:06:33]

Nit: Rename |distance_squared| (and maybe also |closest_distance_squared|). 
Maybe the comment should note "Note: Using LengthSquared() is cheaper than using
Length(), and fine since we only care about relative distances, not absolute
ones."

[danakj, 2012/10/29 23:21:41]

Done.

     if (closest_distance < 0 || closest_distance > distance) {
       target_location = center;
       closest_distance = distance;