[core] Make the BackgroundScheduler a singleton

- Do not carry it over everywhere as parameter, it is a shared
  instance anyway and the lifecycle is pretty much the app lifecycle
  from the moment we instantiate a map.
- Rename to BackgroundScheduler because it is a Scheduler that will
  do tasks in the background, we don't make assumptions if it is a
  thread pool or a single thread.
- Most importantly, remove the dependency from `core` on `platform`.

1 files changed, 12 insertions, 0 deletions

diff --git a/platform/node/src/node_thread_pool.cpp b/platform/node/src/node_thread_pool.cpp
index 1f37565e8a..de403c605c 100644
--- a/platform/node/src/node_thread_pool.cpp
+++ b/platform/node/src/node_thread_pool.cpp
@@ -2,6 +2,7 @@
 #include "util/async_queue.hpp"
 
 #include <mbgl/actor/mailbox.hpp>
+#include <mbgl/platform/background_scheduler.hpp>
 
 namespace node_mbgl {
 
@@ -35,3 +36,14 @@ void NodeThreadPool::Worker::WorkComplete() {
 }
 
 } // namespace node_mbgl
+
+namespace mbgl {
+namespace platform {
+
+Scheduler& GetBackgroundScheduler() {
+    static node_mbgl::NodeThreadPool pool;
+    return pool;
+}
+
+} // namespace platform
+} // namespace mbgl