[Impeller] avoid expensive texture labeling w/ no validation layers.

impeller/renderer/backend/vulkan/texture_vk.cc

@@ -15,12 +15,19 @@ TextureVK::TextureVK(std::weak_ptr<Context> context,
                      std::shared_ptr<TextureSourceVK> source)
     : Texture(source->GetTextureDescriptor()),
       context_(std::move(context)),
-      source_(std::move(source)) {}
+      source_(std::move(source)) {
+#ifdef IMPELLER_DEBUG
+  has_validation_layers_ = HasValidationLayers();
+#endif  // IMPELLER_DEBUG
+}
 
 TextureVK::~TextureVK() = default;
 
 void TextureVK::SetLabel(std::string_view label) {
 #ifdef IMPELLER_DEBUG
+  if (!has_validation_layers_) {
+    return;
+  }
   auto context = context_.lock();
   if (!context) {
     // The context may have died.

impeller/renderer/backend/vulkan/texture_vk.h

@@ -77,6 +77,7 @@ class TextureVK final : public Texture, public BackendCast<TextureVK, Texture> {
  private:
   std::weak_ptr<Context> context_;
   std::shared_ptr<TextureSourceVK> source_;
+  bool has_validation_layers_ = false;
 
   // |Texture|
   void SetLabel(std::string_view label) override;