[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`.

2 files changed, 3 insertions, 11 deletions

diff --git a/platform/macos/core-files.json b/platform/macos/core-files.json
index 9ec41f651a..abeda5796b 100644
--- a/platform/macos/core-files.json
+++ b/platform/macos/core-files.json
@@ -13,9 +13,7 @@
         "platform/default/src/mbgl/gl/headless_frontend.cpp",
         "platform/default/src/mbgl/map/map_snapshotter.cpp",
         "platform/default/src/mbgl/text/bidi.cpp",
-        "platform/default/src/mbgl/util/default_thread_pool.cpp",
         "platform/default/src/mbgl/util/png_writer.cpp",
-        "platform/default/src/mbgl/util/shared_thread_pool.cpp",
         "platform/default/src/mbgl/util/thread_local.cpp",
         "platform/default/src/mbgl/util/utf.cpp"
     ],
@@ -24,9 +22,7 @@
         "mbgl/util/image+MGLAdditions.hpp": "platform/darwin/include/mbgl/util/image+MGLAdditions.hpp",
         "mbgl/gl/headless_backend.hpp": "platform/default/include/mbgl/gl/headless_backend.hpp",
         "mbgl/gl/headless_frontend.hpp": "platform/default/include/mbgl/gl/headless_frontend.hpp",
-        "mbgl/map/map_snapshotter.hpp": "platform/default/include/mbgl/map/map_snapshotter.hpp",
-        "mbgl/util/default_thread_pool.hpp": "platform/default/include/mbgl/util/default_thread_pool.hpp",
-        "mbgl/util/shared_thread_pool.hpp": "platform/default/include/mbgl/util/shared_thread_pool.hpp"
+        "mbgl/map/map_snapshotter.hpp": "platform/default/include/mbgl/map/map_snapshotter.hpp"
     },
     "private_headers": {
         "CFHandle.hpp": "platform/darwin/src/CFHandle.hpp"
diff --git a/platform/macos/src/MGLMapView.mm b/platform/macos/src/MGLMapView.mm
index e9259cf907..77eb300aef 100644
--- a/platform/macos/src/MGLMapView.mm
+++ b/platform/macos/src/MGLMapView.mm
@@ -31,7 +31,6 @@
 #import <mbgl/annotation/annotation.hpp>
 #import <mbgl/map/camera.hpp>
 #import <mbgl/storage/reachability.h>
-#import <mbgl/util/default_thread_pool.hpp>
 #import <mbgl/style/image.hpp>
 #import <mbgl/renderer/renderer.hpp>
 #import <mbgl/gl/renderer_backend.hpp>
@@ -43,7 +42,6 @@
 #import <mbgl/util/chrono.hpp>
 #import <mbgl/util/exception.hpp>
 #import <mbgl/util/run_loop.hpp>
-#import <mbgl/util/shared_thread_pool.hpp>
 #import <mbgl/util/string.hpp>
 #import <mbgl/util/projection.hpp>
 
@@ -164,7 +162,6 @@ public:
     mbgl::Map *_mbglMap;
     MGLMapViewImpl *_mbglView;
     std::unique_ptr<MGLRenderFrontend> _rendererFrontend;
-    std::shared_ptr<mbgl::ThreadPool> _mbglThreadPool;
 
     NSPanGestureRecognizer *_panGestureRecognizer;
     NSMagnificationGestureRecognizer *_magnificationGestureRecognizer;
@@ -283,10 +280,9 @@ public:
     NSURL *legacyCacheURL = [cachesDirectoryURL URLByAppendingPathComponent:@"cache.db"];
     [[NSFileManager defaultManager] removeItemAtURL:legacyCacheURL error:NULL];
 
-    _mbglThreadPool = mbgl::sharedThreadPool();
     MGLRendererConfiguration *config = [MGLRendererConfiguration currentConfiguration];
 
-    auto renderer = std::make_unique<mbgl::Renderer>(*_mbglView, config.scaleFactor, *_mbglThreadPool, config.cacheDir, config.localFontFamilyName);
+    auto renderer = std::make_unique<mbgl::Renderer>(*_mbglView, config.scaleFactor, config.cacheDir, config.localFontFamilyName);
     BOOL enableCrossSourceCollisions = !config.perSourceCollisions;
     _rendererFrontend = std::make_unique<MGLRenderFrontend>(std::move(renderer), self, *_mbglView, true);
 
@@ -302,7 +298,7 @@ public:
     resourceOptions.withCachePath([[MGLOfflineStorage sharedOfflineStorage] mbglCachePath])
                    .withAssetPath([NSBundle mainBundle].resourceURL.path.UTF8String);
 
-    _mbglMap = new mbgl::Map(*_rendererFrontend, *_mbglView, *_mbglThreadPool, mapOptions, resourceOptions);
+    _mbglMap = new mbgl::Map(*_rendererFrontend, *_mbglView, mapOptions, resourceOptions);
 
     // Install the OpenGL layer. Interface Builder’s synchronous drawing means
     // we can’t display a map, so don’t even bother to have a map layer.