Limit Mojo messages recursion depth

mojo/public/interfaces/bindings/tests/validation_test_interfaces.mojom

Index: mojo/public/interfaces/bindings/tests/validation_test_interfaces.mojom
diff --git a/mojo/public/interfaces/bindings/tests/validation_test_interfaces.mojom b/mojo/public/interfaces/bindings/tests/validation_test_interfaces.mojom
index 705650bc18774a4cbc672337735c489d2e58c9b3..5d8296a7b10993052c526fb8df1ad1459ee26b8d 100644
--- a/mojo/public/interfaces/bindings/tests/validation_test_interfaces.mojom
+++ b/mojo/public/interfaces/bindings/tests/validation_test_interfaces.mojom
@@ -92,6 +92,10 @@ interface ConformanceTestInterface {
   Method18(UnionA? param0);
 };
 
+interface RecursionDepthTestInterface {

[yzshen1, 2016/09/06 17:03:10]

I think it may make sense to add it to ConformanceTestInterface. And we need to
make JavaScript and Java validation pass this test, too.

WDYT? 

[tibell, 2016/09/07 05:41:20]

Moved it into ConformanceTestInterface.

I agree with should look at Java and JS too. I'd prefer to do that in a separate
CL.

+  Method0(Recursive recursive);
+};
+
 struct BasicStruct {
   int32 a;
 };
@@ -117,3 +121,8 @@ struct StructWithEnum {
     A, B, C, D
   };
 };
+
+// This is used to test that deeply recursive structures don't blow the stack.
+struct Recursive {
+  Recursive? recursive;
+};