Made it possible to register a "one-time use" ResourceHandler

CefSharp/CefSharp.csproj

@@ -199,6 +199,7 @@
     <Compile Include="PdfPrintSettings.cs" />
     <Compile Include="ICookieManager.cs" />
     <Compile Include="IMenuModel.cs" />
+    <Compile Include="ResourceFactoryItem.cs" />
     <Compile Include="Structs\ViewRect.cs" />
     <Compile Include="ISslInfo.cs" />
     <Compile Include="Structs\KeyEvent.cs" />

CefSharp/DefaultResourceHandlerFactory.cs

@@ -18,43 +18,57 @@ public class DefaultResourceHandlerFactory : IResourceHandlerFactory
         /// <summary>
         /// Resource handler thread safe dictionary
         /// </summary>
-        public ConcurrentDictionary<string, IResourceHandler> Handlers { get; private set; }
+        public ConcurrentDictionary<string, ResourceFactoryItem> Handlers { get; private set; }
 
         /// <summary>
         /// Create a new instance of DefaultResourceHandlerFactory
         /// </summary>
         /// <param name="comparer">string equality comparer</param>
         public DefaultResourceHandlerFactory(IEqualityComparer<string> comparer = null)
         {
-            Handlers = new ConcurrentDictionary<string, IResourceHandler>(comparer ?? StringComparer.OrdinalIgnoreCase);
+            Handlers = new ConcurrentDictionary<string, ResourceFactoryItem>(comparer ?? StringComparer.OrdinalIgnoreCase);
         }
 
         /// <summary>
-        /// Register handler with the specified Url
+        /// Register a handler for the specified Url
         /// </summary>
         /// <param name="url">url</param>
         /// <param name="handler">handler</param>
+        /// <param name="persist">Whether or not the handler should be used once (false) or until manually unregistered (true)</param>
         /// <returns>returns true if the Url was successfully parsed into a Uri otherwise false</returns>
-        public virtual bool RegisterHandler(string url, IResourceHandler handler)
+        public virtual bool RegisterHandler(string url, IResourceHandler handler, bool persist)
         {
             Uri uri;
             if (Uri.TryCreate(url, UriKind.Absolute, out uri))
             {
-                Handlers.AddOrUpdate(uri.AbsoluteUri, handler, (k, v) => handler);
+                ResourceFactoryItem entry = new ResourceFactoryItem(handler, persist);
+
+                Handlers.AddOrUpdate(uri.AbsoluteUri, entry, (k, v) => entry);
                 return true;
             }
             return false;
         }
 
+        /// <summary>
+        /// Register a persistant handler for the specified Url
+        /// </summary>
+        /// <param name="url">url</param>
+        /// <param name="handler">handler</param>
+        /// <returns>returns true if the Url was successfully parsed into a Uri otherwise false</returns>
+        public virtual bool RegisterHandler(string url, IResourceHandler handler)
+        {
+            return RegisterHandler(url, handler, true);
+        }
+
         /// <summary>
         /// Unregister a handler for the specified Url
         /// </summary>
         /// <param name="url">Url</param>
         /// <returns>returns true if successfully removed</returns>
         public virtual bool UnregisterHandler(string url)
         {
-            IResourceHandler handler;
-            return Handlers.TryRemove(url, out handler);
+            ResourceFactoryItem entry;
+            return Handlers.TryRemove(url, out entry);
         }
 
         /// <summary>
@@ -77,10 +91,19 @@ public virtual IResourceHandler GetResourceHandler(IWebBrowser browserControl, I
         {
             try
             {
-                IResourceHandler handler;
-                Handlers.TryGetValue(request.Url, out handler);
+                ResourceFactoryItem entry;
+
+                if (Handlers.TryGetValue(request.Url, out entry))
+                {
+                    if (!entry.Persist)
+                    {
+                        Handlers.TryRemove(request.Url, out entry);
+                    }
+
+                    return entry.Handler;
+                }
 
-                return handler;
+                return null;
             }
             finally
             {

CefSharp/ResourceFactoryItem.cs

@@ -0,0 +1,27 @@
+// Copyright © 2010-2017 The CefSharp Authors. All rights reserved.
+//
+// Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.
+
+namespace CefSharp
+{
+    public class ResourceFactoryItem
+    {
+        /// <summary>
+        /// The handler for a specific Url
+        /// </summary>
+        public IResourceHandler Handler { get; private set; }
+
+        /// <summary>
+        /// Whether or not the handler should be used once (false) or until manually unregistered (true)
+        /// </summary>
+        public bool Persist { get; private set; }
+
+        /// <param name="handler">The handler for a specific Url</param>
+        /// <param name="persist">Whether or not the handler should be used once (false) or until manually unregistered (true)</param>
+        public ResourceFactoryItem(IResourceHandler handler, bool persist)
+        {
+            Handler = handler;
+            Persist = persist;
+        }
+    }
+}