Add Dart_LibraryId method unblocking landing 45613003. TBR

runtime/vm/mirrors_api_impl.cc

Index: runtime/vm/mirrors_api_impl.cc
diff --git a/runtime/vm/mirrors_api_impl.cc b/runtime/vm/mirrors_api_impl.cc
index caa1346c835d518a7cedd953138812d73a57f989..af7c0963b08157b20415fe2170823592fa7dcb00 100644
--- a/runtime/vm/mirrors_api_impl.cc
+++ b/runtime/vm/mirrors_api_impl.cc
@@ -323,6 +323,19 @@ DART_EXPORT Dart_Handle Dart_LibraryName(Dart_Handle library) {
   return Api::NewHandle(isolate, name.raw());
 }
 
+DART_EXPORT Dart_Handle Dart_LibraryId(Dart_Handle library,
+                                       intptr_t* library_id) {
+  Isolate* isolate = Isolate::Current();
+  DARTSCOPE(isolate);
+  const Library& lib = Api::UnwrapLibraryHandle(isolate, library);
+  if (lib.IsNull()) {
+    RETURN_TYPE_ERROR(isolate, library, Library);
+  }

[siva, 2013/10/28 02:27:48]

Usually we report an error when NULL pointers are passed in, in this case it
would be

  if (library_id == NULL) {
    RETURN_NULL_ERROR(library_id);
  }

+  if (library_id != NULL) {
+    *library_id = lib.index();
+  }

[siva, 2013/10/28 02:27:48]

Once the NULL check is in place you could remove this != NULL check.

+  return Api::Success();
+}
 
 DART_EXPORT Dart_Handle Dart_LibraryGetClassNames(Dart_Handle library) {
   Isolate* isolate = Isolate::Current();