Implemented StructTraits for cc::TextureMailbox

cc/ipc/traits_test_service.mojom

Index: cc/ipc/traits_test_service.mojom
diff --git a/cc/ipc/traits_test_service.mojom b/cc/ipc/traits_test_service.mojom
index 88919497bb6ed5d107dccbe41b9202f55a9cfb42..b77c187cda8fe07bd847c5e03c48bbce8a90c927 100644
--- a/cc/ipc/traits_test_service.mojom
+++ b/cc/ipc/traits_test_service.mojom
@@ -17,6 +17,7 @@ import "cc/ipc/shared_quad_state.mojom";
 import "cc/ipc/surface_id.mojom";
 import "cc/ipc/surface_reference.mojom";
 import "cc/ipc/surface_sequence.mojom";
+import "cc/ipc/texture_mailbox.mojom";
 import "cc/ipc/transferable_resource.mojom";
 
 // All functions on this interface echo their arguments to test StructTraits
@@ -60,6 +61,10 @@ interface TraitsTestService {
   EchoSurfaceSequence(SurfaceSequence s) => (SurfaceSequence pass);
 
   [Sync]
+  EchoTextureMailbox(TextureMailbox t) =>
+      (TextureMailbox pass);
+
+  [Sync]
   EchoTransferableResource(TransferableResource t) =>
       (TransferableResource pass);
 };