Implement gfx::Transform StructTraits unit test

ui/gfx/mojo/traits_test_service.mojom

Index: ui/gfx/mojo/traits_test_service.mojom
diff --git a/ui/gfx/mojo/transform.mojom b/ui/gfx/mojo/traits_test_service.mojom
similarity index 61%
copy from ui/gfx/mojo/transform.mojom
copy to ui/gfx/mojo/traits_test_service.mojom
index 1ce0e753f5f55f78ffdc893169308002f6678a42..9eca0d1f5a7b7c3207756da78849a37db344bd5a 100644
--- a/ui/gfx/mojo/transform.mojom
+++ b/ui/gfx/mojo/traits_test_service.mojom
@@ -4,8 +4,8 @@
 
 module gfx.mojom;
 
-// See ui/gfx/transform.h.
-struct Transform {
-  // Row major order.
-  array<float, 16> matrix;
+import "ui/gfx/mojo/transform.mojom";
+
+interface TraitsTestService {

[sadrul, 2016/06/01 16:17:38]

I think if you make this [Sync], then you don't need the lambda/capture?

[Fady Samuel, 2016/06/01 16:20:19]

Making it sync on one thread would deadlock I think.

[yzshen1, 2016/06/01 16:22:24]

If you mean the sender and the receiver on the same thread, it won't deadlock.

Sync services will be able to reenter any ongoing sync calls on the same thread.

[Fady Samuel, 2016/06/01 16:32:31]

Cool! I just tried it and it works and simplifies the unit test! w00t! I should
go back and update the other unit tests at some point.

+  EchoTransform(Transform t) => (Transform pass);
 };