Make request and reparse pure virtual

src/mbgl/map/vector_tile_data.cpp

@@ -7,6 +7,9 @@
 #include <mbgl/platform/log.hpp>
 #include <mbgl/text/collision_tile.hpp>
 #include <mbgl/util/pbf.hpp>
+#include <mbgl/storage/resource.hpp>
+#include <mbgl/storage/response.hpp>
+#include <mbgl/storage/file_source.hpp>
 #include <mbgl/util/worker.hpp>
 #include <mbgl/util/work_request.hpp>
 #include <mbgl/style/style.hpp>
@@ -32,6 +35,41 @@ VectorTileData::~VectorTileData() {
     style.glyphAtlas->removeGlyphs(reinterpret_cast<uintptr_t>(this));
 }
 
+void VectorTileData::request(Worker& worker,
+                       float pixelRatio,
+                       const std::function<void()>& callback) {
+    std::string url = source.tileURL(id, pixelRatio);
+    state = State::loading;
+
+    FileSource* fs = util::ThreadContext::getFileSource();
+    req = fs->request({ Resource::Kind::Tile, url }, util::RunLoop::current.get()->get(), [url, callback, &worker, this](const Response &res) {
+        req = nullptr;
+
+        if (res.status != Response::Successful) {
+            std::stringstream message;
+            message <<  "Failed to load [" << url << "]: " << res.message;
+            setError(message.str());
+            callback();
+            return;
+        }
+
+        state = State::loaded;
+        data = res.data;
+
+        // Schedule tile parsing in another thread
+        reparse(worker, callback);
+    });
+}
+
+bool VectorTileData::reparse(Worker& worker, std::function<void()> callback) {
+    if (!mayStartParsing()) {
+        return false;
+    }
+
+    workRequest = worker.send([this] { parse(); endParsing(); }, callback);
+    return true;
+}
+
 void VectorTileData::parse() {
     if (getState() != State::loaded && getState() != State::partial) {
         return;