Add systemPreferences.subscribeNotification

atom/browser/api/atom_api_system_preferences_mac.mm

@@ -4,19 +4,54 @@
 
 #include "atom/browser/api/atom_api_system_preferences.h"
 
+#include <map>
+
 #import <Cocoa/Cocoa.h>
 
+#include "base/strings/sys_string_conversions.h"
+
 namespace atom {
 
 namespace api {
 
-#if defined(OS_MACOSX)
+namespace {
+
+int g_next_id = 0;
+
+// The map to convert |id| to |int|.
+std::map<int, id> g_id_map;
+
+}  // namespace
+
+int SystemPreferences::SubscribeNotification(const std::string& name,
+                                             const base::Closure& callback) {
+  int request_id = g_next_id++;
+  __block base::Closure copied_callback = callback;
+  g_id_map[request_id] = [[NSDistributedNotificationCenter defaultCenter]
+      addObserverForName:base::SysUTF8ToNSString(name)
+      object:nil
+      queue:nil
+      usingBlock:^(NSNotification* notification) {
+        copied_callback.Run();
+      }
+  ];
+  return request_id;
+}
+
+void SystemPreferences::UnsubscribeNotification(int request_id) {
+  auto iter = g_id_map.find(request_id);
+  if (iter != g_id_map.end()) {
+    id observer = iter->second;
+    [[NSDistributedNotificationCenter defaultCenter] removeObserver:observer];
+    g_id_map.erase(iter);
+  }
+}
+
 bool SystemPreferences::IsDarkMode() {
   NSString* mode = [[NSUserDefaults standardUserDefaults]
       stringForKey:@"AppleInterfaceStyle"];
   return [mode isEqualToString:@"Dark"];
 }
-#endif
 
 }  // namespace api