Add SurfaceReference class.

cc/surfaces/BUILD.gn

Index: cc/surfaces/BUILD.gn
diff --git a/cc/surfaces/BUILD.gn b/cc/surfaces/BUILD.gn
index 836576e703d296b0626bf81c796e8e2186de7714..b106a0180a0c29e943e0e04c31516207d7049dc2 100644
--- a/cc/surfaces/BUILD.gn
+++ b/cc/surfaces/BUILD.gn
@@ -12,6 +12,8 @@ cc_source_set("surface_id") {
     "local_frame_id.h",
     "surface_id.cc",
     "surface_id.h",
+    "surface_reference.cc",
+    "surface_reference.h",
     "surface_sequence.h",
     "surface_sequence_generator.cc",
     "surface_sequence_generator.h",
@@ -19,6 +21,7 @@ cc_source_set("surface_id") {
 
   deps = [
     "//base",
+    "//mojo/public/cpp/bindings:struct_traits",
   ]
 }