Core - Add TryGetBrowserCoreById

- Can be used to obtain an IBrowser reference by Browser Identifier (Id).
- Added a couple of basic unit tests.

Author: amaitland

CefSharp.Core.Runtime/ManagedCefBrowserAdapter.cpp

@@ -195,7 +195,12 @@ namespace CefSharp
 
         IBrowser^ ManagedCefBrowserAdapter::GetBrowser(int browserId)
         {
-            return _clientAdapter->GetBrowserWrapper(browserId);
+            if (_clientAdapter.get())
+            {
+                return _clientAdapter->GetBrowserWrapper(browserId);
+            }
+
+            return nullptr;
         }
 
         IJavascriptCallbackFactory^ ManagedCefBrowserAdapter::JavascriptCallbackFactory::get()

CefSharp.Test/OffScreen/OffScreenBrowserBasicFacts.cs

@@ -745,6 +745,35 @@ public async Task CanWaitForBrowserInitialLoadAfterLoad()
             }
         }
 
+        [Fact]
+        public async Task CanCallTryGetBrowserCoreByIdWithInvalidId()
+        {
+            using (var browser = new ChromiumWebBrowser("http://www.google.com"))
+            {
+                var response = await browser.WaitForInitialLoadAsync();
+
+                var result = browser.TryGetBrowserCoreById(100, out IBrowser browserCore);
+
+                Assert.False(result);
+                Assert.Null(browserCore);
+            }
+        }
+
+        [Fact]
+        public async Task CanCallTryGetBrowserCoreByIdWithOwnId()
+        {
+            using (var browser = new ChromiumWebBrowser("http://www.google.com"))
+            {
+                var response = await browser.WaitForInitialLoadAsync();
+
+                var result = browser.TryGetBrowserCoreById(browser.BrowserCore.Identifier, out IBrowser browserCore);
+
+                Assert.True(result);
+                Assert.NotNull(browserCore);
+                Assert.Equal(browser.BrowserCore.Identifier, browserCore.Identifier);
+            }
+        }
+
 #if DEBUG
         [Fact]
         public async Task CanLoadMultipleBrowserInstancesSequentially()

CefSharp/IWebBrowser.cs

@@ -160,5 +160,14 @@ public interface IWebBrowser : IChromiumWebBrowserBase
         /// </summary>
         /// <returns>browser instance or null</returns>
         IBrowser GetBrowser();
+
+        /// <summary>
+        /// Try and get a reference to the <see cref="IBrowser"/> instance that matches the <paramref name="browserId"/>.
+        /// Primarily used for geting a reference to the <see cref="IBrowser"/> used by popups.
+        /// </summary>
+        /// <param name="browserId">browser Id</param>
+        /// <param name="browser">When this method returns, contains the <see cref="IBrowser"/> object reference that matches the specified <paramref name="browserId"/>, or null if no matching instance found.</param>
+        /// <returns>true if a <see cref="IBrowser"/> instance was found matching <paramref name="browserId"/>; otherwise, false.</returns>
+        bool TryGetBrowserCoreById(int browserId, out IBrowser browser);
     }
 }

CefSharp/Internals/Partial/ChromiumWebBrowser.Partial.cs

@@ -375,6 +375,23 @@ public Task<LoadUrlAsyncResponse> WaitForInitialLoadAsync()
             return initialLoadTaskCompletionSource.Task;
         }
 
+        /// <inheritdoc/>
+        public bool TryGetBrowserCoreById(int browserId, out IBrowser browser)
+        {
+            var browserAdapter = managedCefBrowserAdapter;
+
+            if (IsDisposed || browserAdapter == null || browserAdapter.IsDisposed)
+            {
+                browser = null;
+
+                return false;
+            }
+
+            browser = browserAdapter.GetBrowser(browserId);
+
+            return browser != null;
+        }
+
         private void InitialLoad(bool? isLoading, CefErrorCode? errorCode)
         {
             if(IsDisposed)