Make RenderPass::Id an isolated class

mojo/examples/surfaces_app/child_impl.cc

Index: mojo/examples/surfaces_app/child_impl.cc
diff --git a/mojo/examples/surfaces_app/child_impl.cc b/mojo/examples/surfaces_app/child_impl.cc
index 578c65c000ed9225befecf2c008de4bcb9d488bd..afefe09dc7540c3fdb035482ac6b96881c6f0739 100644
--- a/mojo/examples/surfaces_app/child_impl.cc
+++ b/mojo/examples/surfaces_app/child_impl.cc
@@ -22,6 +22,7 @@ namespace mojo {
 namespace examples {
 
 using cc::RenderPass;
+using cc::RenderPassId;
 using cc::DrawQuad;
 using cc::SolidColorDrawQuad;
 using cc::DelegatedFrameData;
@@ -63,7 +64,7 @@ void ChildImpl::Draw() {
   surface_->CreateSurface(mojo::SurfaceId::From(id_),
                           mojo::Size::From(size_));
   gfx::Rect rect(size_);
-  RenderPass::Id id(1, 1);
+  RenderPassId id(1, 1);
   scoped_ptr<RenderPass> pass = RenderPass::Create();
   pass->SetNew(id, rect, rect, gfx::Transform());