Adding GetStreamInfo functionality (and passing corresponding unit test).

command_buffer/common/cross/resource.h

Index: command_buffer/common/cross/resource.h
===================================================================
--- command_buffer/common/cross/resource.h	(revision 19749)
+++ command_buffer/common/cross/resource.h	(working copy)
@@ -134,6 +134,13 @@
 };
 }  // namespace effect_param
 
+namespace effect_stream {
+struct Desc {
+  Uint32 semantic;         // the semantic type
+  Uint32 semantic_index;
+};
+}  // namespace effect_stream
+
 namespace texture {
 // Texture flags.
 enum Flags {