Implement res:// protocol for WebView, MIME type handling.

Robust.Client.WebView/IWebViewManager.cs

@@ -1,7 +1,40 @@
-namespace Robust.Client.WebView
+using System.Diagnostics.CodeAnalysis;
+
+namespace Robust.Client.WebView
 {
     public interface IWebViewManager
     {
         IWebViewWindow CreateBrowserWindow(BrowserWindowCreateParameters createParams);
+
+        /// <summary>
+        /// Overrides file extension -> mime type mappings for the <c>res://</c> protocol.
+        /// </summary>
+        /// <remarks>
+        /// <para>
+        /// The built-in <c>res://</c> protocol needs to guess MIME types to report to CEF when resolving files.
+        /// A limited set of extensions have pre-set MIME types in the engine.
+        /// This method allows you to replace or add entries if need be.
+        /// </para>
+        /// <para>
+        /// This method is thread safe.
+        /// </para>
+        /// </remarks>
+        /// <param name="extension">
+        /// The extension to specify the MIME type for.
+        /// The argument must not include the starting "." of the file extension.
+        /// </param>
+        /// <param name="mimeType">The mime type for this file extension.</param>
+        /// <seealso cref="TryGetResourceMimeType"/>
+        void SetResourceMimeType(string extension, string mimeType);
+
+        /// <summary>
+        /// Tries to resolve an entry from the <see cref="SetResourceMimeType"/> list.
+        /// </summary>
+        /// <remarks>
+        /// <para>
+        /// This method is thread safe.
+        /// </para>
+        /// </remarks>
+        bool TryGetResourceMimeType(string extension, [NotNullWhen(true)] out string? mimeType);
     }
 }