Enhance chrome.app.window API with title property

extensions/common/api/app_window.idl

Index: extensions/common/api/app_window.idl
diff --git a/extensions/common/api/app_window.idl b/extensions/common/api/app_window.idl
index 9e3ba8c2488cea44ee5db6244103786dfa524cb2..a00d9df5730db207e5f37ab0ead6bb84cd0f97b7 100644
--- a/extensions/common/api/app_window.idl
+++ b/extensions/common/api/app_window.idl
@@ -235,6 +235,10 @@ namespace app.window {
     // is set to true. The URL should be a global or an extension local URL.
     DOMString? icon;
 
+    // Title of the window. A window can have its own title when shownInShelf
+    // is set to true. The title string value acts as a tooltip for the window.
+    DOMString? title;
+
     // Frame type: <code>none</code> or <code>chrome</code> (defaults to
     // <code>chrome</code>). For <code>none</code>, the
     // <code>-webkit-app-region</code> CSS property can be used to apply