[XAM/CONTENT] - Implement XamContentRegisterChangeCallback

- Implement XamContentRegisterChangeCallback
- Callback used subfunction within XContentInstall

src/xenia/kernel/xam/xam_content.cc

@@ -794,6 +794,11 @@ dword_result_t XamContentLaunchImageInternal_entry(lpvoid_t content_data_ptr,
 
 DECLARE_XAM_EXPORT1(XamContentLaunchImageInternal, kContent, kStub);
 
+void XamContentRegisterChangeCallback_entry(dword_t callback) {
+  kernel_state()->xam_state()->SetContentRegisterCallback(callback);
+}
+DECLARE_XAM_EXPORT1(XamContentRegisterChangeCallback, kContent, kImplemented);
+
 dword_result_t XamContentGetDeviceVolumePath_entry(dword_t device_id,
                                                    lpvoid_t path_ptr,
                                                    dword_t path_size,

src/xenia/kernel/xam/xam_state.cc

@@ -72,6 +72,10 @@ void XamState::LoadSpaInfo(const SpaInfo* info) {
   user_tracker_->UpdateSpaInfo(spa_info_.get());
 }
 
+void XamState::SetContentRegisterCallback(uint32_t callback) {
+  content_register_callback = callback;
+}
+
 }  // namespace xam
 }  // namespace kernel
 }  // namespace xe

src/xenia/kernel/xam/xam_state.h

@@ -57,9 +57,12 @@ class XamState {
   //
   void LoadSpaInfo(const SpaInfo* info);
 
+  void SetContentRegisterCallback(uint32_t callback);
+
   X_DASH_APP_INFO dash_app_info_ = {};
   uint32_t dash_backstack_nodes_count_ = 0;
   X_DASH_BACKSTACK_DATA dash_backstack_data_[2] = {};
+  uint32_t content_register_callback = 0;
 
   std::atomic<int32_t> xam_dialogs_shown_ = {0};
   std::atomic<int32_t> xam_nui_dialogs_shown_ = {0};