[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, 7 deletions

diff --git a/platform/darwin/src/MGLMapSnapshotter.mm b/platform/darwin/src/MGLMapSnapshotter.mm
index 171f24e4d0..65bed2cf42 100644
--- a/platform/darwin/src/MGLMapSnapshotter.mm
+++ b/platform/darwin/src/MGLMapSnapshotter.mm
@@ -8,9 +8,7 @@
 #import <mbgl/map/camera.hpp>
 #import <mbgl/storage/resource_options.hpp>
 #import <mbgl/storage/default_file_source.hpp>
-#import <mbgl/util/default_thread_pool.hpp>
 #import <mbgl/util/string.hpp>
-#import <mbgl/util/shared_thread_pool.hpp>
 
 #import "MGLOfflineStorage_Private.h"
 #import "MGLGeometry_Private.h"
@@ -125,7 +123,6 @@ const CGFloat MGLSnapshotterMinimumPixelSize = 64;
 @end
 
 @implementation MGLMapSnapshotter {
-    std::shared_ptr<mbgl::ThreadPool> _mbglThreadPool;
     std::unique_ptr<mbgl::MapSnapshotter> _mbglMapSnapshotter;
     std::unique_ptr<mbgl::Actor<mbgl::MapSnapshotter::Callback>> _snapshotCallback;
 }
@@ -176,7 +173,6 @@ const CGFloat MGLSnapshotterMinimumPixelSize = 64;
 
     _mbglMapSnapshotter.reset();
     _snapshotCallback.reset();
-    _mbglThreadPool.reset();
     
     self.terminated = YES;
 }
@@ -591,8 +587,6 @@ const CGFloat MGLSnapshotterMinimumPixelSize = 64;
     _options = options;
 
     auto mbglFileSource = [[MGLOfflineStorage sharedOfflineStorage] mbglFileSource];
-
-    _mbglThreadPool = mbgl::sharedThreadPool();
     
     std::string styleURL = std::string([options.styleURL.absoluteString UTF8String]);
     std::pair<bool, std::string> style = std::make_pair(false, styleURL);
@@ -630,7 +624,7 @@ const CGFloat MGLSnapshotterMinimumPixelSize = 64;
 
     // Create the snapshotter
     _mbglMapSnapshotter = std::make_unique<mbgl::MapSnapshotter>(
-        _mbglThreadPool, style, size, pixelRatio, cameraOptions, coordinateBounds, config.cacheDir, config.localFontFamilyName, resourceOptions);
+        style, size, pixelRatio, cameraOptions, coordinateBounds, config.cacheDir, config.localFontFamilyName, resourceOptions);
 }
 
 @end