feat(page): introduce Page.PauseAsync (microsoft#1168)

src/PlaywrightSharp/BrowserContext.cs

@@ -331,6 +331,8 @@ public async Task<StorageState> GetStorageStateAsync(string path = null)
             return state;
         }
 
+        internal Task PauseAsync() => Channel.PauseAsync();
+
         internal void OnRoute(Route route, Request request)
         {
             foreach (var item in _routes)

src/PlaywrightSharp/IPage.cs

@@ -29,7 +29,6 @@
 using System.IO;
 using System.Text.Json;
 using System.Text.RegularExpressions;
-using System.Threading;
 using System.Threading.Tasks;
 using PlaywrightSharp.Input;
 
@@ -1803,5 +1802,17 @@ Task<byte[]> GetPdfAsync(
         /// The default value can be changed by using the <see cref="IBrowserContext.DefaultTimeout"/> or <see cref="IPage.DefaultTimeout"/>.</param>
         /// <returns>A <see cref="Task"/> that completes when the message is processed by the browser.</returns>
         Task<bool> IsVisibleAsync(string selector, int? timeout = null);
+
+        /// <summary>
+        /// Pauses script execution. Playwright will stop executing the script and wait for the user to either press 'Resume' button
+        /// in the page overlay or to call `playwright.resume()` in the DevTools console.
+        ///
+        /// User can inspect selectors or perform manual steps while paused. Resume will continue running the original script from
+        /// the place it was paused.
+        ///
+        /// > NOTE: This method requires Playwright to be started in a headed mode, with a falsy `headless` value in the <seealso cref="IBrowserType.LaunchAsync(bool?, string[], string, bool?, string, string, bool?, int?, bool?, int?, bool?, string[], Dictionary{string, string}, Dictionary{string, object}, ProxySettings, bool?, bool?, bool?, bool?)"/>.
+        /// </summary>
+        /// <returns>A <see cref="Task"/> that completes when the message is processed by the browser.</returns>
+        Task PauseAsync();
     }
 }

src/PlaywrightSharp/Page.cs

@@ -948,6 +948,9 @@ public Task TapAsync(string selector, Modifier[] modifiers = null, Point? positi
         /// <inheritdoc />
         public Task<bool> IsVisibleAsync(string selector, int? timeout = null) => MainFrame.IsVisibleAsync(true, selector, timeout);
 
+        /// <inheritdoc />
+        public Task PauseAsync() => Context.PauseAsync();
+
         internal void OnFrameNavigated(Frame frame)
             => FrameNavigated?.Invoke(this, new FrameEventArgs(frame));
 

src/PlaywrightSharp/Transport/Channels/BrowserContextChannel.cs

@@ -222,5 +222,8 @@ internal Task<CDPSessionChannel> NewCDPSessionAsync(IPage page)
 
         internal Task<StorageState> GetStorageStateAsync()
             => Connection.SendMessageToServerAsync<StorageState>(Guid, "storageState", null);
+
+        internal Task PauseAsync()
+            => Connection.SendMessageToServerAsync(Guid, "pause", null);
     }
 }