Merge from vscode 8b5ebbb1b8f6b2127bbbd551ac10cc080482d5b4 (#5041)

src/vs/vscode.d.ts

@@ -5714,6 +5714,21 @@ declare module 'vscode' {
 		copy?(source: Uri, destination: Uri, options: { overwrite: boolean }): void | Thenable<void>;
 	}
 
+	/**
+	 * Defines a port mapping used for localhost inside the webview.
+	 */
+	export interface WebviewPortMapping {
+		/**
+		 * Localhost port to remap inside the webview.
+		 */
+		readonly webviewPort: number;
+
+		/**
+		 * Destination port. The `webviewPort` is resolved to this port.
+		 */
+		readonly extensionHostPort: number;
+	}
+
 	/**
 	 * Content settings for a webview.
 	 */
@@ -5740,6 +5755,18 @@ declare module 'vscode' {
 		 * Pass in an empty array to disallow access to any local resources.
 		 */
 		readonly localResourceRoots?: ReadonlyArray<Uri>;
+
+		/**
+		 * Mappings of localhost ports used inside the webview.
+		 *
+		 * Port mapping allow webviews to transparently define how localhost ports are resolved. This can be used
+		 * to allow using a static localhost port inside the webview that is resolved to random port that a service is
+		 * running on.
+		 *
+		 * If a webview accesses localhost content, we recomend that you specify port mappings even if
+		 * the `webviewPort` and `extensionHostPort` ports are the same.
+		 */
+		readonly portMapping?: ReadonlyArray<WebviewPortMapping>;
 	}
 
 	/**