Add TaggedScheduler, couple lifetime of tasks and orchestrator (#2398)

src/mbgl/tile/geometry_tile.cpp

@@ -169,10 +169,11 @@ GeometryTile::GeometryTile(const OverscaledTileID& id_, std::string sourceID_, c
     : Tile(Kind::Geometry, id_),
       ImageRequestor(parameters.imageManager),
       sourceID(std::move(sourceID_)),
-      threadPool(Scheduler::GetBackground()),
+      threadPool(parameters.threadPool),
       mailbox(std::make_shared<Mailbox>(*Scheduler::GetCurrent())),
-      worker(threadPool,
+      worker(parameters.threadPool, // Scheduler reference for the Actor retainer
              ActorRef<GeometryTile>(*this, mailbox),
+             parameters.threadPool,
              id_,
              sourceID,
              obsolete,
@@ -194,7 +195,7 @@ GeometryTile::~GeometryTile() {
     imageManager->removeRequestor(*this);
 
     if (layoutResult) {
-        threadPool->runOnRenderThread(
+        threadPool.runOnRenderThread(
             [layoutResult_{std::move(layoutResult)}, atlasTextures_{std::move(atlasTextures)}]() {});
     }
 }