[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, 4 insertions, 4 deletions

diff --git a/platform/node/src/node_map.cpp b/platform/node/src/node_map.cpp
index 7156a1f1bf..0a7da3a83a 100644
--- a/platform/node/src/node_map.cpp
+++ b/platform/node/src/node_map.cpp
@@ -630,8 +630,8 @@ void NodeMap::cancel() {
         reinterpret_cast<NodeMap *>(h->data)->renderFinished();
     });
 
-    frontend = std::make_unique<mbgl::HeadlessFrontend>(mbgl::Size{ 256, 256 }, pixelRatio, threadpool);
-    map = std::make_unique<mbgl::Map>(*frontend, mapObserver, threadpool,
+    frontend = std::make_unique<mbgl::HeadlessFrontend>(mbgl::Size{ 256, 256 }, pixelRatio);
+    map = std::make_unique<mbgl::Map>(*frontend, mapObserver,
                                       mbgl::MapOptions().withSize(frontend->getSize())
                                       .withPixelRatio(pixelRatio)
                                       .withMapMode(mode)
@@ -1214,8 +1214,8 @@ NodeMap::NodeMap(v8::Local<v8::Object> options)
             : true;
     }())
     , mapObserver(NodeMapObserver())
-    , frontend(std::make_unique<mbgl::HeadlessFrontend>(mbgl::Size { 256, 256 }, pixelRatio, threadpool))
-    , map(std::make_unique<mbgl::Map>(*frontend, mapObserver, threadpool,
+    , frontend(std::make_unique<mbgl::HeadlessFrontend>(mbgl::Size { 256, 256 }, pixelRatio))
+    , map(std::make_unique<mbgl::Map>(*frontend, mapObserver,
                                       mbgl::MapOptions().withSize(frontend->getSize())
                                       .withPixelRatio(pixelRatio)
                                       .withMapMode(mode)