Added webdriver support for App v2.

chrome/test/webdriver/commands/target_locator_commands.cc

Index: chrome/test/webdriver/commands/target_locator_commands.cc
diff --git a/chrome/test/webdriver/commands/target_locator_commands.cc b/chrome/test/webdriver/commands/target_locator_commands.cc
index 5b28a66a3c6b3b352ed652106c6ca47ca39d3eca..9fb37b42b20ae3d334bffed17c906c54470fa6ff 100644
--- a/chrome/test/webdriver/commands/target_locator_commands.cc
+++ b/chrome/test/webdriver/commands/target_locator_commands.cc
@@ -52,7 +52,8 @@ void WindowHandlesCommand::ExecuteGet(Response* const response) {
   }
   base::ListValue* id_list = new base::ListValue();
   for (size_t i = 0; i < views.size(); ++i) {
-    if (!views[i].view_id.IsTab())
+    if (!views[i].view_id.IsTab() &&
+        views[i].view_id.GetId().type() != AutomationId::kTypeAppShell)
       continue;
     id_list->Append(Value::CreateStringValue(
         WebViewIdToString(views[i].view_id)));