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

chrome/browser/ui/window_snapshot/window_snapshot_mac.mm

 // 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 "chrome/browser/ui/window_snapshot/window_snapshot.h"
 
 #import <Cocoa/Cocoa.h>
 
 #include "base/logging.h"
 #include "base/mac/scoped_cftyperef.h"
@@ skipping 10 matching lines @@
   gfx::Rect screen_bounds = gfx::Rect(NSRectToCGRect([screen frame]));
   gfx::Rect window_bounds = gfx::Rect(NSRectToCGRect([window frame]));
 
   // Flip window coordinates based on the primary screen.
   window_bounds.set_y(
       screen_bounds.height() - window_bounds.y() - window_bounds.height());
 
   // Convert snapshot bounds relative to window into bounds relative to
   // screen.
   gfx::Rect screen_snapshot_bounds = gfx::Rect(
-      window_bounds.origin().Add(snapshot_bounds.origin()),
+      window_bounds.origin().Add(snapshot_bounds.DistanceFromOrigin()),
       snapshot_bounds.size());
 
   DCHECK_LE(screen_snapshot_bounds.right(), window_bounds.right());
   DCHECK_LE(screen_snapshot_bounds.bottom(), window_bounds.bottom());
 
   png_representation->clear();
 
   // Make sure to grab the "window frame" view so we get current tab +
   // tabstrip.
   NSView* view = [[window contentView] superview];
@@ skipping 12 matching lines @@
     return false;
 
   png_representation->assign(buf, buf + length);
   DCHECK(!png_representation->empty());
 
   return true;
 }
 
 }  // namespace internal
 }  // namespace chrome