Ensure menu item ordering for DbusMenu::OnGetGroupProperties

Ubuntu's top bar expects properties returned in the order they were
requested.  The returned properties have IDs associated with them, so
ordering really shouldn't be necessary. Alas, keep them ordered to
appease Unity.

BUG=981201
R=thestig

Change-Id: I2907c264cc4346a47aa6304f7302c6d58555c9cb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1716958
Commit-Queue: Thomas Anderson <thomasanderson@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/master@{#682553}

components/dbus/menu/menu.cc

@@ -327,12 +327,12 @@ void DbusMenu::OnGetGroupProperties(ScopedMethodResponse* response) {
   dbus::MessageReader id_reader(nullptr);
   if (!response->reader().PopArray(&id_reader))
     return;
-  std::set<int32_t> ids;
+  std::vector<int32_t> ids;
   while (id_reader.HasMoreData()) {
     int32_t id;
     if (!id_reader.PopInt32(&id))
       return;
-    ids.insert(id);
+    ids.push_back(id);
   }
 
   std::set<std::string> property_filter;
@@ -349,15 +349,14 @@ void DbusMenu::OnGetGroupProperties(ScopedMethodResponse* response) {
   dbus::MessageWriter& writer = response->Writer();
   dbus::MessageWriter item_writer(nullptr);
   writer.OpenArray("(ia{sv})", &item_writer);
-  for (const auto& item_pair : items_) {
-    if (!ids.empty() && !base::Contains(ids, item_pair.first))
-      continue;
+
+  auto write_item = [&](int32_t id, const MenuItem& item) {
     dbus::MessageWriter struct_writer(nullptr);
     item_writer.OpenStruct(&struct_writer);
-    struct_writer.AppendInt32(item_pair.first);
+    struct_writer.AppendInt32(id);
     dbus::MessageWriter property_writer(nullptr);
     struct_writer.OpenArray("{sv}", &property_writer);
-    for (const auto& property_pair : item_pair.second->properties) {
+    for (const auto& property_pair : item.properties) {
       if (!property_filter.empty() &&
           !base::Contains(property_filter, property_pair.first)) {
         continue;
@@ -370,7 +369,19 @@ void DbusMenu::OnGetGroupProperties(ScopedMethodResponse* response) {
     }
     struct_writer.CloseContainer(&property_writer);
     item_writer.CloseContainer(&struct_writer);
+  };
+
+  if (ids.empty()) {
+    for (const auto& item_pair : items_)
+      write_item(item_pair.first, *item_pair.second);
+  } else {
+    for (int32_t id : ids) {
+      auto it = items_.find(id);
+      if (it != items_.end())
+        write_item(id, *it->second);
+    }
   }
+
   writer.CloseContainer(&item_writer);
 }