core: Eliminate more uses of Core::System::GetInstance(). (#7313)

src/core/frontend/applets/default_applets.cpp

@@ -9,7 +9,7 @@
 
 namespace Frontend {
 void RegisterDefaultApplets(Core::System& system) {
-    system.RegisterSoftwareKeyboard(std::make_shared<DefaultKeyboard>());
+    system.RegisterSoftwareKeyboard(std::make_shared<DefaultKeyboard>(system));
     system.RegisterMiiSelector(std::make_shared<DefaultMiiSelector>());
 }
 } // namespace Frontend

src/core/frontend/applets/swkbd.cpp

@@ -144,10 +144,12 @@ const KeyboardData& SoftwareKeyboard::ReceiveData() {
     return data;
 }
 
+DefaultKeyboard::DefaultKeyboard(Core::System& system_) : system(system_) {}
+
 void DefaultKeyboard::Execute(const Frontend::KeyboardConfig& config_) {
     SoftwareKeyboard::Execute(config_);
 
-    auto cfg = Service::CFG::GetModule(Core::System::GetInstance());
+    auto cfg = Service::CFG::GetModule(system);
     std::string username = Common::UTF16ToUTF8(cfg->GetUsername());
     switch (this->config.button_config) {
     case ButtonConfig::None:

src/core/frontend/applets/swkbd.h

@@ -8,6 +8,10 @@
 #include <vector>
 #include "common/assert.h"
 
+namespace Core {
+class System;
+}
+
 namespace Frontend {
 
 enum class AcceptedInput {
@@ -137,8 +141,12 @@ protected:
 
 class DefaultKeyboard final : public SoftwareKeyboard {
 public:
+    explicit DefaultKeyboard(Core::System& system_);
     void Execute(const KeyboardConfig& config) override;
     void ShowError(const std::string& error) override;
+
+private:
+    Core::System& system;
 };
 
 } // namespace Frontend