Core - WebBrowserExtensions throw explicit ObjectDisposedException if IsDisposed

- Make it clear that the ChromiumWebBrowser instance has been disposed.
  Previously when the browser was disposed BrowserCore would be null.
  An explicit ObjectDisposedException is now thrown.

Author: amaitland

CefSharp.Test/OffScreen/OffScreenBrowserBasicFacts.cs

@@ -64,6 +64,33 @@ public async Task CanLoadGoogle()
             }
         }
 
+        [Fact]
+        public async Task ShouldRespectDisposed()
+        {
+            ChromiumWebBrowser browser;
+
+            using (browser = new ChromiumWebBrowser(CefExample.DefaultUrl))
+            {
+                var response = await browser.WaitForInitialLoadAsync();
+
+                Assert.True(response.Success);
+
+                var mainFrame = browser.GetMainFrame();
+                Assert.True(mainFrame.IsValid);
+                Assert.Equal(CefExample.DefaultUrl, mainFrame.Url);
+                Assert.Equal(200, response.HttpStatusCode);
+
+                output.WriteLine("Url {0}", mainFrame.Url);
+            }
+
+            Assert.True(browser.IsDisposed);
+
+            Assert.Throws<ObjectDisposedException>(() =>
+            {
+                browser.Copy();
+            });
+        }
+
         [Fact]
         public async Task CanLoadInvalidDomain()
         {

CefSharp.Test/WinForms/WinFormsBrowserBasicFacts.cs

@@ -2,7 +2,9 @@
 //
 // Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.
 
+using System;
 using System.Threading.Tasks;
+using CefSharp.Example;
 using CefSharp.WinForms;
 using Xunit;
 using Xunit.Abstractions;
@@ -126,5 +128,32 @@ public async Task CanSetRequestContext()
                 output.WriteLine("Url {0}", mainFrame.Url);
             }
         }
+
+        [WinFormsFact]
+        public async Task ShouldRespectDisposed()
+        {
+            ChromiumWebBrowser browser;
+
+            using (browser = new ChromiumWebBrowser(CefExample.DefaultUrl))
+            {
+                browser.Size = new System.Drawing.Size(1024, 768);
+                browser.CreateControl();
+
+                await browser.WaitForInitialLoadAsync();
+
+                var mainFrame = browser.GetMainFrame();
+                Assert.True(mainFrame.IsValid);
+                Assert.Equal(CefExample.DefaultUrl, mainFrame.Url);
+
+                output.WriteLine("Url {0}", mainFrame.Url);
+            }
+
+            Assert.True(browser.IsDisposed);
+
+            Assert.Throws<ObjectDisposedException>(() =>
+            {
+                browser.Copy();
+            });
+        }
     }
 }

CefSharp.Test/Wpf/WpfBrowserBasicFacts.cs

@@ -2,8 +2,10 @@
 //
 // Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.
 
+using System;
 using System.Threading.Tasks;
 using System.Windows;
+using CefSharp.Example;
 using CefSharp.Wpf;
 using Xunit;
 using Xunit.Abstractions;
@@ -111,5 +113,23 @@ public async Task CanSetRequestContextViaBuilder()
                 output.WriteLine("Url {0}", mainFrame.Url);
             }
         }
+
+        [WpfFact]
+        public async Task ShouldRespectDisposed()
+        {
+            ChromiumWebBrowser browser;
+
+            using (browser = new ChromiumWebBrowser(null, CefExample.DefaultUrl, new Size(1024, 786)))
+            {
+                await browser.WaitForInitialLoadAsync();
+            }
+
+            Assert.True(browser.IsDisposed);
+
+            var ex = Assert.Throws<ObjectDisposedException>(() =>
+            {
+                browser.Copy();
+            });
+        }
     }
 }