[core] Merge RenderLayer::uploadBuckets into RenderSource::startRender

src/mbgl/renderer/sources/render_image_source.cpp

@@ -27,10 +27,10 @@ bool RenderImageSource::isLoaded() const {
 }
 
 void RenderImageSource::startRender(Painter& painter) {
-
     if (!isLoaded()) {
         return;
     }
+
     matrices.clear();
 
     for (size_t i = 0; i < tileIds.size(); i++) {
@@ -40,6 +40,10 @@ void RenderImageSource::startRender(Painter& painter) {
         matrix::multiply(matrix, painter.projMatrix, matrix);
         matrices.push_back(matrix);
     }
+
+    if (bucket->needsUpload() && shouldRender) {
+        bucket->upload(painter.context);
+    }
 }
 
 void RenderImageSource::finishRender(Painter& painter) {
@@ -63,12 +67,6 @@ std::vector<Feature> RenderImageSource::querySourceFeatures(const SourceQueryOpt
     return {};
 }
 
-void RenderImageSource::upload(gl::Context& context) {
-    if (isLoaded() && bucket->needsUpload() && shouldRender) {
-        bucket->upload(context);
-    }
-}
-
 void RenderImageSource::update(Immutable<style::Source::Impl> baseImpl_,
                                const std::vector<Immutable<Layer::Impl>>&,
                                const bool needsRendering,