Implement cc::SurfaceId StructTraits

components/mus/ws/BUILD.gn

Index: components/mus/ws/BUILD.gn
diff --git a/components/mus/ws/BUILD.gn b/components/mus/ws/BUILD.gn
index 0ec414739620ffc342fdfb42fd940237c398c98a..09b2f2f8cf796ae721f7b5a239cc1c784169efc3 100644
--- a/components/mus/ws/BUILD.gn
+++ b/components/mus/ws/BUILD.gn
@@ -92,6 +92,7 @@ source_set("lib") {
   deps = [
     "//base",
     "//cc",
+    "//cc/ipc:interfaces",

[Ken Rockot(use gerrit already), 2016/05/26 16:58:22]

Please fix these dependencies while you're here.

To wit, at least //cc/ipc:interfaces and //components/mus/public/interfaces
should be in public_deps rather than deps, because they're exposed by this
target's headers.

There are probably several other targets in deps here that should be in
public_deps as well. Sadly there are similar mistakes alllll over src/, but it's
particularly troublesome when generated files are involved as it can easily lead
to latent build flake.

As a general rule, if it's exposed by a header that your dependents might
include (e.g. mus/mus_app.cc includes window_tree.h), it MUST be in public_deps.

[Fady Samuel, 2016/05/26 17:45:09]

I've moved the interfaces over. I haven't done an exhaustive move of things that
should move to public_deps.

[Ken Rockot(use gerrit already), 2016/05/26 17:55:10]

I'd kind of prefer that you did. It doesn't seem like much more effort to just
correct these things now.

[Fady Samuel, 2016/05/26 19:54:29]

Seems like everything should be a public dep here. Done.

     "//cc/surfaces",
     "//cc/surfaces:surface_id",
     "//components/mus/common:mus_common",