implement NativeTheme API with shouldUseDarkColors

ElectronNET.API/Electron.cs

@@ -78,5 +78,10 @@
         /// Allows you to execute native Lock and Unlock process.       
         /// </summary>
         public static PowerMonitor PowerMonitor { get { return PowerMonitor.Instance; } }
+
+        /// <summary>
+        /// Read and respond to changes in Chromium's native color theme.
+        /// </summary>
+        public static NativeTheme NativeTheme { get { return NativeTheme.Instance; } }
     }
 }

ElectronNET.API/NativeTheme.cs

@@ -0,0 +1,55 @@
+using System.Threading.Tasks;
+
+namespace ElectronNET.API
+{
+    /// <summary>
+    /// Read and respond to changes in Chromium's native color theme.
+    /// </summary>
+    public sealed class NativeTheme
+    {
+        private static NativeTheme _nativeTheme;
+        private static object _syncRoot = new object();
+
+        internal NativeTheme() { }
+
+        internal static NativeTheme Instance
+        {
+            get
+            {
+                if (_nativeTheme == null)
+                {
+                    lock (_syncRoot)
+                    {
+                        if (_nativeTheme == null)
+                        {
+                            _nativeTheme = new NativeTheme();
+                        }
+                    }
+                }
+
+                return _nativeTheme;
+            }
+        }
+
+        /// <summary>
+        /// A `Boolean` for if the OS / Chromium currently has a dark mode enabled or is
+        /// being instructed to show a dark-style UI.If you want to modify this value you
+        /// should use `themeSource` below.
+        /// </summary>
+        /// <returns></returns>
+        public Task<bool> ShouldUseDarkColorsAsync()
+        {
+            var taskCompletionSource = new TaskCompletionSource<bool>();
+
+            BridgeConnector.Socket.On("nativeTheme-shouldUseDarkColors-completed", (shouldUseDarkColors) => {
+                BridgeConnector.Socket.Off("nativeTheme-shouldUseDarkColors-completed");
+
+                taskCompletionSource.SetResult((bool)shouldUseDarkColors);
+            });
+
+            BridgeConnector.Socket.Emit("nativeTheme-shouldUseDarkColors");
+
+            return taskCompletionSource.Task;
+        }
+    }
+}