Mojo C++ bindings: make the generator use STL/WTF string/vector/map by default.

content/test/BUILD.gn

Index: content/test/BUILD.gn
diff --git a/content/test/BUILD.gn b/content/test/BUILD.gn
index 8c8e58d39fb83a6efda3cceafdd6f3947b2c8110..3a6d603a4a748b5cd52cff55118d97c2a8b3938c 100644
--- a/content/test/BUILD.gn
+++ b/content/test/BUILD.gn
@@ -266,12 +266,16 @@ mojom("content_test_mojo_bindings") {
   sources = [
     "../public/test/test_mojo_service.mojom",
   ]
+
+  use_new_wrapper_types = false
 }
 
 mojom("web_ui_test_mojo_bindings") {
   sources = [
     "data/web_ui_test_mojo_bindings.mojom",
   ]
+
+  use_new_wrapper_types = false
 }
 
 # GYP version //content/content_tests.gypi:layouttest_support_content