Update Surface ID Terminology

cc/ipc/surface_id_struct_traits.h

Index: cc/ipc/surface_id_struct_traits.h
diff --git a/cc/ipc/surface_id_struct_traits.h b/cc/ipc/surface_id_struct_traits.h
index bafadf9cdfde7d7e4630e0bee410e40cb78a3807..162b39804ed9b2270bf12df278b20868f0fe0c9c 100644
--- a/cc/ipc/surface_id_struct_traits.h
+++ b/cc/ipc/surface_id_struct_traits.h
@@ -14,16 +14,14 @@ namespace mojo {
 // respectively.
 template <typename T>
 struct StructTraits<T, cc::SurfaceId> {
-  static uint32_t id_namespace(const cc::SurfaceId& id) {
-    return id.id_namespace();
-  }
+  static uint32_t client_id(const cc::SurfaceId& id) { return id.client_id(); }
 
   static uint32_t local_id(const cc::SurfaceId& id) { return id.local_id(); }
 
   static uint64_t nonce(const cc::SurfaceId& id) { return id.nonce(); }
 
   static bool Read(typename T::DataView data, cc::SurfaceId* out) {
-    *out = cc::SurfaceId(data.id_namespace(), data.local_id(), data.nonce());
+    *out = cc::SurfaceId(data.client_id(), data.local_id(), data.nonce());
     return true;
   }
 };