Remove unused Settings::ToString. (flutter#8642)

This was used in some embedder implementations. But that was a while ago.

common/settings.cc

@@ -14,44 +14,4 @@ Settings::Settings(const Settings& other) = default;
 
 Settings::~Settings() = default;
 
-std::string Settings::ToString() const {
-  std::stringstream stream;
-  stream << "Settings: " << std::endl;
-  stream << "vm_snapshot_data_path: " << vm_snapshot_data_path << std::endl;
-  stream << "vm_snapshot_instr_path: " << vm_snapshot_instr_path << std::endl;
-  stream << "isolate_snapshot_data_path: " << isolate_snapshot_data_path
-         << std::endl;
-  stream << "isolate_snapshot_instr_path: " << isolate_snapshot_instr_path
-         << std::endl;
-  stream << "application_library_path: " << application_library_path
-         << std::endl;
-  stream << "temp_directory_path: " << temp_directory_path << std::endl;
-  stream << "dart_flags:" << std::endl;
-  for (const auto& dart_flag : dart_flags) {
-    stream << "    " << dart_flag << std::endl;
-  }
-  stream << "start_paused: " << start_paused << std::endl;
-  stream << "trace_skia: " << trace_skia << std::endl;
-  stream << "trace_startup: " << trace_startup << std::endl;
-  stream << "trace_systrace: " << trace_systrace << std::endl;
-  stream << "dump_skp_on_shader_compilation: " << dump_skp_on_shader_compilation
-         << std::endl;
-  stream << "endless_trace_buffer: " << endless_trace_buffer << std::endl;
-  stream << "enable_dart_profiling: " << enable_dart_profiling << std::endl;
-  stream << "disable_dart_asserts: " << disable_dart_asserts << std::endl;
-  stream << "enable_observatory: " << enable_observatory << std::endl;
-  stream << "observatory_port: " << observatory_port << std::endl;
-  stream << "ipv6: " << ipv6 << std::endl;
-  stream << "use_test_fonts: " << use_test_fonts << std::endl;
-  stream << "enable_software_rendering: " << enable_software_rendering
-         << std::endl;
-  stream << "log_tag: " << log_tag << std::endl;
-  stream << "icu_initialization_required: " << icu_initialization_required
-         << std::endl;
-  stream << "icu_data_path: " << icu_data_path << std::endl;
-  stream << "assets_dir: " << assets_dir << std::endl;
-  stream << "assets_path: " << assets_path << std::endl;
-  return stream.str();
-}
-
 }  // namespace flutter

common/settings.h

@@ -145,8 +145,6 @@ struct Settings {
       fml::UniqueFD::traits_type::InvalidValue();
   std::string assets_path;
   std::string flx_path;
-
-  std::string ToString() const;
 };
 
 }  // namespace flutter