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

webkit/plugins/ppapi/ppapi_plugin_instance.cc

Index: webkit/plugins/ppapi/ppapi_plugin_instance.cc
diff --git a/webkit/plugins/ppapi/ppapi_plugin_instance.cc b/webkit/plugins/ppapi/ppapi_plugin_instance.cc
index cd78ea8db33873f5b3880ad0c07ca198c5f09fc2..73498d6c0de7eed94413b14969c1d2d73f593e5e 100644
--- a/webkit/plugins/ppapi/ppapi_plugin_instance.cc
+++ b/webkit/plugins/ppapi/ppapi_plugin_instance.cc
@@ -1194,9 +1194,9 @@ bool PluginInstance::GetBitmapForOptimizedPluginPaint(
   }
 
   *dib = image_data->PlatformImage()->GetTransportDIB();
-  plugin_backing_store_rect.Offset(plugin_origin);
+  plugin_backing_store_rect.Offset(plugin_origin.OffsetFromOrigin());
   *location = plugin_backing_store_rect;
-  clip_page.Offset(plugin_origin);
+  clip_page.Offset(plugin_origin.OffsetFromOrigin());
   *clip = clip_page;
   // The plugin scale factor is inverted, e.g. for a device scale factor of 2x
   // the plugin scale factor is 0.5.