Add mojo structs for ScopedFD and ScopedHandle.

mojo/common/BUILD.gn

Index: mojo/common/BUILD.gn
diff --git a/mojo/common/BUILD.gn b/mojo/common/BUILD.gn
index 60d523f78eb2c0ea720a42aa2b3dc58a8f535398..b813961a1485a0f4cd721166c52385333312f8e6 100644
--- a/mojo/common/BUILD.gn
+++ b/mojo/common/BUILD.gn
@@ -16,6 +16,7 @@ mojom("common_custom_types") {
   sources = [
     "file.mojom",
     "file_path.mojom",
+    "platform_handle.mojom",
     "string16.mojom",
     "time.mojom",
     "unguessable_token.mojom",
@@ -51,6 +52,7 @@ component("common_base") {
 mojom("test_common_custom_types") {
   sources = [
     "test_common_custom_types.mojom",
+    "test_invalid_typemapped_type.mojom",
     "traits_test_service.mojom",
   ]
   public_deps = [
@@ -96,6 +98,12 @@ source_set("struct_traits") {
   sources = [
     "common_custom_types_struct_traits.cc",
     "common_custom_types_struct_traits.h",
+    "common_custom_types_struct_traits_posix.cc",
+    "common_custom_types_struct_traits_posix.h",
+    "common_custom_types_struct_traits_win.cc",
+    "common_custom_types_struct_traits_win.h",
+    "invalid_typemapped_type.h",
+    "platform_handle.h",
   ]
   deps = [
     ":common_custom_types_shared_cpp_sources",