Introduce cc StructTraits unit tests

cc/BUILD.gn

Index: cc/BUILD.gn
diff --git a/cc/BUILD.gn b/cc/BUILD.gn
index 1aafbe219f8ca4d82f83bdd5589d42ef7306b999..3002a9fbfb46e09be55e98b4242751eba8a7aa98 100644
--- a/cc/BUILD.gn
+++ b/cc/BUILD.gn
@@ -800,6 +800,7 @@ test("cc_unittests") {
     "input/scrollbar_animation_controller_thinning_unittest.cc",
     "input/top_controls_manager_unittest.cc",
     "ipc/cc_param_traits_unittest.cc",
+    "ipc/struct_traits_unittest.cc",
     "layers/heads_up_display_layer_impl_unittest.cc",
     "layers/heads_up_display_unittest.cc",
     "layers/layer_impl_unittest.cc",
@@ -949,6 +950,7 @@ test("cc_unittests") {
     ":test_support",
     "//base/test:test_support",
     "//cc/ipc",
+    "//cc/ipc:test_interfaces",
     "//cc/proto",
     "//cc/surfaces",
     "//cc/surfaces:surface_id",
@@ -957,6 +959,8 @@ test("cc_unittests") {
     "//gpu/command_buffer/client:gles2_interface",
     "//gpu/command_buffer/common:gles2_utils",
     "//media",
+    "//mojo/edk/system",
+    "//mojo/public/cpp/bindings",
     "//testing/gmock",
     "//testing/gtest",
     "//ui/events:events_base",