tree - allow to add aria label as option

src/vs/base/parts/tree/browser/tree.ts

@@ -605,6 +605,7 @@ export interface ITreeOptions {
 	bare?:boolean;
 	useShadows?:boolean;
 	paddingOnRow?:boolean;
+	ariaLabel?:string;
 }
 
 export interface ITreeContext extends ITreeConfiguration {

src/vs/base/parts/tree/browser/treeView.ts

@@ -461,9 +461,14 @@ export class TreeView extends HeightMap implements IScrollable {
 
 		this.domNode = document.createElement('div');
 		this.domNode.className = 'monaco-tree';
-		this.domNode.setAttribute('role', 'tree');
 		this.domNode.tabIndex = 0;
 
+		// ARIA
+		this.domNode.setAttribute('role', 'tree');
+		if (this.context.options.ariaLabel) {
+			this.domNode.setAttribute('aria-label', this.context.options.ariaLabel);
+		}
+
 		if (this.context.options.alwaysFocused) {
 			DOM.addClass(this.domNode, 'focused');
 		}

src/vs/workbench/parts/files/browser/views/explorerView.ts

@@ -314,7 +314,8 @@ export class ExplorerView extends CollapsibleViewletView {
 			filter: this.filter,
 			dnd: dnd
 		}, {
-			autoExpandSingleChildren: true
+			autoExpandSingleChildren: true,
+			ariaLabel: nls.localize('explorerTreeAriaLabel', "Explorer Files Tree")
 		});
 
 		this.toDispose.push(lifecycle.toDisposable(() => renderer.dispose()));