Mojo C++ bindings: sync call support for associated interfaces and master interfaces

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

Index: mojo/public/interfaces/bindings/tests/test_sync_methods.mojom
diff --git a/mojo/public/interfaces/bindings/tests/test_sync_methods.mojom b/mojo/public/interfaces/bindings/tests/test_sync_methods.mojom
index e2147bccd740bfa12289d188f84282a2e5454bb0..fd42ec1acc43315c5932717d2fc777e83b4758c2 100644
--- a/mojo/public/interfaces/bindings/tests/test_sync_methods.mojom
+++ b/mojo/public/interfaces/bindings/tests/test_sync_methods.mojom
@@ -27,3 +27,15 @@ interface TestSync {
 
   AsyncEcho(int32 value) => (int32 result);
 };
+
+interface TestSyncMaster {
+  [Sync]
+  Ping() => ();
+
+  [Sync]
+  Echo(int32 value) => (int32 result);
+
+  AsyncEcho(int32 value) => (int32 result);
+
+  SendInterface(associated TestSync ptr);
+};