[core] Move markContextDestroyed() to the RenderLayer

src/mbgl/renderer/layers/render_custom_layer.cpp

@@ -42,6 +42,10 @@ bool RenderCustomLayer::hasCrossfade() const {
     return false;
 }
 
+void RenderCustomLayer::markContextDestroyed() {
+    contextDestroyed = true;
+}
+
 std::unique_ptr<Bucket> RenderCustomLayer::createBucket(const BucketParameters&, const std::vector<const RenderLayer*>&) const {
     assert(false);
     return nullptr;

src/mbgl/renderer/layers/render_custom_layer.hpp

@@ -14,16 +14,13 @@ public:
     void evaluate(const PropertyEvaluationParameters&) override;
     bool hasTransition() const override;
     bool hasCrossfade() const override;
+    void markContextDestroyed() final;
 
     std::unique_ptr<Bucket> createBucket(const BucketParameters&, const std::vector<const RenderLayer*>&) const final;
     void render(PaintParameters&, RenderSource*) final;
 
     const style::CustomLayer::Impl& impl() const;
 
-    void markContextDestroyed() {
-        contextDestroyed = true;
-    };
-
 private:
     bool contextDestroyed = false;
     std::shared_ptr<style::CustomLayerHost> host;

src/mbgl/renderer/render_layer.cpp

@@ -75,6 +75,10 @@ void RenderLayer::setRenderTiles(std::vector<std::reference_wrapper<RenderTile>>
     renderTiles = std::move(tiles);
 }
 
+void RenderLayer::markContextDestroyed() {
+    // no-op
+}
+
 void RenderLayer::checkRenderability(const PaintParameters& parameters,
                                      const uint32_t activeBindingCount) {
     // Only warn once for every layer.

src/mbgl/renderer/render_layer.hpp

@@ -91,8 +91,8 @@ public:
     Immutable<style::Layer::Impl> baseImpl;
     void setImpl(Immutable<style::Layer::Impl>);
 
+    virtual void markContextDestroyed();
     friend std::string layoutKey(const RenderLayer&);
-
 protected:
     // Checks whether the current hardware can render this layer. If it can't, we'll show a warning
     // in the console to inform the developer.

src/mbgl/renderer/renderer_impl.cpp

@@ -69,13 +69,13 @@ Renderer::Impl::~Impl() {
     assert(BackendScope::exists());
 
     if (contextLost) {
-        // Signal all RenderCustomLayers that the context was lost
-        // before cleaning up
+        // Signal all RenderLayers that the context was lost
+        // before cleaning up. At the moment, only CustomLayer is
+        // interested whether rendering context is lost. However, it would be
+        // beneficial for dynamically loaded or other custom built-in plugins.
         for (const auto& entry : renderLayers) {
             RenderLayer& layer = *entry.second;
-            if (layer.is<RenderCustomLayer>()) {
-                layer.as<RenderCustomLayer>()->markContextDestroyed();
-            }
+            layer.markContextDestroyed();
         }
     }
 };