Change origin from string to Uri as that's what the code is expecting - so github.com wasn't working, http://www.github.com does

Improved the documentation a little

Author: amaitland

CefSharp.Core/RequestContext.h

@@ -286,15 +286,15 @@ namespace CefSharp
         // |callback| will be executed on the UI thread after completion.
         ///
         /*--cef()--*/
-        virtual Task<ResolveCallbackResult>^ ResolveHostAsync(String^ origin)
+        virtual Task<ResolveCallbackResult>^ ResolveHostAsync(Uri^ origin)
         {
             ThrowIfDisposed();
 
             auto callback = gcnew TaskResolveCallbackHandler();
 
             CefRefPtr<CefResolveCallback> callbackWrapper = new CefResolveCallbackAdapter(callback);
 
-            _requestContext->ResolveHost(StringUtils::ToNative(origin), callbackWrapper);
+            _requestContext->ResolveHost(StringUtils::ToNative(origin->AbsoluteUri), callbackWrapper);
 
             return callback->Task;
         }
@@ -306,13 +306,13 @@ namespace CefSharp
         // success. This method must be called on the browser process IO thread.
         ///
         /*--cef(default_retval=ERR_FAILED)--*/
-        virtual CefErrorCode ResolveHostCached(String^ origin, [Out] IList<String^>^ %resolvedIpAddresses)
+        virtual CefErrorCode ResolveHostCached(Uri^ origin, [Out] IList<String^>^ %resolvedIpAddresses)
         {
             ThrowIfDisposed();
 
             std::vector<CefString> addresses;
 
-            auto errorCode =_requestContext->ResolveHostCached(StringUtils::ToNative(origin), addresses);
+            auto errorCode = _requestContext->ResolveHostCached(StringUtils::ToNative(origin->AbsoluteUri), addresses);
 
             resolvedIpAddresses = StringUtils::ToClr(addresses);
 

CefSharp/IRequestContext.cs

@@ -158,7 +158,7 @@ public interface IRequestContext : IDisposable
         /// </summary>
         /// <param name="origin">host name to resolve</param>
         /// <return>A task that represents the Resoolve Host operation. The value of the TResult parameter contains ResolveCallbackResult.</return>
-        Task<ResolveCallbackResult> ResolveHostAsync(string origin);
+        Task<ResolveCallbackResult> ResolveHostAsync(Uri origin);
 
         /// <summary>
         /// Attempts to resolve origin to a list of associated IP addresses using
@@ -168,6 +168,6 @@ public interface IRequestContext : IDisposable
         /// <param name="resolvedIpAddresses">list of resolved IP
         /// addresses or empty list if no cached data is available.</param>
         /// <returns> Returns <see cref="CefErrorCode.None"/> on success</returns>
-        CefErrorCode ResolveHostCached(string origin, out IList<string> resolvedIpAddresses);
+        CefErrorCode ResolveHostCached(Uri origin, out IList<string> resolvedIpAddresses);
     }
 }

CefSharp/IResolveCallback.cs

@@ -13,7 +13,7 @@ public interface IResolveCallback
         /// </summary>
         /// <param name="result">The result code</param>
         /// <param name="resolvedIpAddresses">will be the list of resolved IP addresses or
-        /// null if the resolution failed.</param>
+        /// empty if the resolution failed.</param>
         void OnResolveCompleted(CefErrorCode result, IList<string> resolvedIpAddresses);
     }
 }

CefSharp/ResolveCallbackResult.cs

@@ -8,7 +8,14 @@ namespace CefSharp
 {
     public struct ResolveCallbackResult
     {
+        /// <summary>
+        /// The result code - <see cref="CefErrorCode.None"/> on success
+        /// </summary>
         public CefErrorCode Result { get; private set; }
+
+        /// <summary>
+        /// List of resolved IP addresses or empty if the resolution failed.
+        /// </summary>
         public IList<string> ResolvedIpAddresses { get; private set; }
 
         public ResolveCallbackResult(CefErrorCode result, IList<string> resolvedIpAddresses) : this()