Introduce cc StructTraits unit tests

cc/DEPS

Index: cc/DEPS
diff --git a/cc/DEPS b/cc/DEPS
index f1bdb3fc5b3868841fa7a8b446fa1852ff1e2d71..0cc14d27f82fb9ea5c2cf72fb8d2c2297ba675b3 100644
--- a/cc/DEPS
+++ b/cc/DEPS
@@ -20,3 +20,10 @@ include_rules = [
   "+ui/gl",
   "-cc/blink",
 ]
+
+specific_include_rules = {
+  "run_all_unittests\.cc": [
+    "+mojo/edk/embedder/embedder.h",
+    "+mojo/edk/test/scoped_ipc_support.h",
+  ],
+}