[core] Organize files that were in map folder better

Fixes #996

src/mbgl/tile/raster_tile_data.cpp

@@ -0,0 +1,82 @@
+#include <mbgl/tile/raster_tile_data.hpp>
+#include <mbgl/source/source.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>
+
+using namespace mbgl;
+
+RasterTileData::RasterTileData(const TileID& id_,
+                               float pixelRatio,
+                               const std::string& urlTemplate,
+                               TexturePool &texturePool_,
+                               Worker& worker_,
+                               const std::function<void(std::exception_ptr)>& callback)
+    : TileData(id_),
+      texturePool(texturePool_),
+      worker(worker_) {
+    state = State::loading;
+
+    const Resource resource = Resource::tile(urlTemplate, pixelRatio, id.x, id.y, id.sourceZ);
+    req = util::ThreadContext::getFileSource()->request(resource, [callback, this](Response res) {
+        if (res.error) {
+            callback(std::make_exception_ptr(std::runtime_error(res.error->message)));
+        } else if (res.notModified) {
+            modified = res.modified;
+            expires = res.expires;
+        } else if (res.noContent) {
+            state = State::parsed;
+            modified = res.modified;
+            expires = res.expires;
+            workRequest.reset();
+            bucket.reset();
+            callback(nullptr);
+        } else {
+            modified = res.modified;
+            expires = res.expires;
+
+            // Only overwrite the state when we didn't have a previous tile.
+            if (state == State::loading) {
+                state = State::loaded;
+            }
+
+            workRequest.reset();
+            workRequest = worker.parseRasterTile(std::make_unique<RasterBucket>(texturePool), res.data, [this, callback] (RasterTileParseResult result) {
+                workRequest.reset();
+                if (state != State::loaded) {
+                    return;
+                }
+
+                std::exception_ptr error;
+                if (result.is<std::unique_ptr<Bucket>>()) {
+                    state = State::parsed;
+                    bucket = std::move(result.get<std::unique_ptr<Bucket>>());
+                } else {
+                    error = result.get<std::exception_ptr>();
+                    state = State::obsolete;
+                    bucket.reset();
+                }
+
+                callback(error);
+            });
+        }
+    });
+}
+
+RasterTileData::~RasterTileData() {
+    cancel();
+}
+
+Bucket* RasterTileData::getBucket(StyleLayer const&) {
+    return bucket.get();
+}
+
+void RasterTileData::cancel() {
+    if (state != State::obsolete) {
+        state = State::obsolete;
+    }
+    req = nullptr;
+    workRequest.reset();
+}