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

content/public/common/common_param_traits.h

Index: content/public/common/common_param_traits.h
diff --git a/content/public/common/common_param_traits.h b/content/public/common/common_param_traits.h
index 8128a9e7526007ca47cb8727d33b103e9ae0b3a5..ce5a668ce36b8d71b7ed779ada1601138f314b5f 100644
--- a/content/public/common/common_param_traits.h
+++ b/content/public/common/common_param_traits.h
@@ -33,6 +33,7 @@ class Point;
 class Rect;
 class RectF;
 class Size;
+class Vector2d;
 }  // namespace gfx
 
 namespace net {
@@ -82,6 +83,14 @@ struct CONTENT_EXPORT ParamTraits<gfx::Size> {
 };
 
 template <>
+struct CONTENT_EXPORT ParamTraits<gfx::Vector2d> {
+  typedef gfx::Vector2d param_type;
+  static void Write(Message* m, const param_type& p);
+  static bool Read(const Message* m, PickleIterator* iter, param_type* r);
+  static void Log(const param_type& p, std::string* l);
+};
+
+template <>
 struct CONTENT_EXPORT ParamTraits<gfx::Rect> {
   typedef gfx::Rect param_type;
   static void Write(Message* m, const param_type& p);