[txt] Add back FontCollection::SetDefaultFontManager (#8410)

third_party/txt/src/txt/font_collection.cc

@@ -91,6 +91,10 @@ void FontCollection::SetupDefaultFontManager() {
   default_font_manager_ = GetDefaultFontManager();
 }
 
+void FontCollection::SetDefaultFontManager(sk_sp<SkFontMgr> font_manager) {
+  default_font_manager_ = font_manager;
+}
+
 void FontCollection::SetAssetFontManager(sk_sp<SkFontMgr> font_manager) {
   asset_font_manager_ = font_manager;
 }

third_party/txt/src/txt/font_collection.h

@@ -41,6 +41,7 @@ class FontCollection : public std::enable_shared_from_this<FontCollection> {
   size_t GetFontManagersCount() const;
 
   void SetupDefaultFontManager();
+  void SetDefaultFontManager(sk_sp<SkFontMgr> font_manager);
   void SetAssetFontManager(sk_sp<SkFontMgr> font_manager);
   void SetDynamicFontManager(sk_sp<SkFontMgr> font_manager);
   void SetTestFontManager(sk_sp<SkFontMgr> font_manager);