[core] Fix performance-unnecessary-value-param errors in header files

As reported by clang-tidy-8.

3 files changed, 4 insertions, 4 deletions

diff --git a/src/mbgl/renderer/image_manager_observer.hpp b/src/mbgl/renderer/image_manager_observer.hpp
index c2ca481d66..947c5a36bc 100644
--- a/src/mbgl/renderer/image_manager_observer.hpp
+++ b/src/mbgl/renderer/image_manager_observer.hpp
@@ -8,7 +8,7 @@ class ImageManagerObserver {
 public:
     virtual ~ImageManagerObserver() = default;
 
-    virtual void onStyleImageMissing(const std::string&, std::function<void()> done) { done(); }
+    virtual void onStyleImageMissing(const std::string&, const std::function<void()>& done) { done(); }
     virtual void onRemoveUnusedStyleImages(const std::vector<std::string>&) {}
 };
 
diff --git a/src/mbgl/renderer/render_orchestrator.cpp b/src/mbgl/renderer/render_orchestrator.cpp
index ac62b71828..77e23d3ab6 100644
--- a/src/mbgl/renderer/render_orchestrator.cpp
+++ b/src/mbgl/renderer/render_orchestrator.cpp
@@ -727,8 +727,8 @@ void RenderOrchestrator::onTileChanged(RenderSource&, const OverscaledTileID&) {
     observer->onInvalidate();
 }
 
-void RenderOrchestrator::onStyleImageMissing(const std::string& id, std::function<void()> done) {
-    observer->onStyleImageMissing(id, std::move(done));
+void RenderOrchestrator::onStyleImageMissing(const std::string& id, const std::function<void()>& done) {
+    observer->onStyleImageMissing(id, done);
 }
 
 void RenderOrchestrator::onRemoveUnusedStyleImages(const std::vector<std::string>& unusedImageIDs) {
diff --git a/src/mbgl/renderer/render_orchestrator.hpp b/src/mbgl/renderer/render_orchestrator.hpp
index 08904e7e5a..5d698f5532 100644
--- a/src/mbgl/renderer/render_orchestrator.hpp
+++ b/src/mbgl/renderer/render_orchestrator.hpp
@@ -100,7 +100,7 @@ private:
     void onTileError(RenderSource&, const OverscaledTileID&, std::exception_ptr) override;
 
     // ImageManagerObserver implementation
-    void onStyleImageMissing(const std::string&, std::function<void()>) override;
+    void onStyleImageMissing(const std::string&, const std::function<void()>&) override;
     void onRemoveUnusedStyleImages(const std::vector<std::string>&) override;
 
     RendererObserver* observer;