[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, 1 insertions, 2 deletions

diff --git a/include/mbgl/style/style.hpp b/include/mbgl/style/style.hpp
index d6fdbd8f2c..4a6a542b88 100644
--- a/include/mbgl/style/style.hpp
+++ b/include/mbgl/style/style.hpp
@@ -11,7 +11,6 @@
 namespace mbgl {
 
 class FileSource;
-class Scheduler;
 
 namespace style {
 
@@ -22,7 +21,7 @@ class Layer;
 
 class Style {
 public:
-    Style(Scheduler&, FileSource&, float pixelRatio);
+    Style(FileSource&, float pixelRatio);
     ~Style();
 
     void loadJSON(const std::string&);