Allow native_viewport to create new native windows on demand on Android.

services/native_viewport/native_viewport_internal.mojom

Index: services/native_viewport/native_viewport_internal.mojom
diff --git a/services/native_viewport/native_viewport_internal.mojom b/services/native_viewport/native_viewport_internal.mojom
new file mode 100644
index 0000000000000000000000000000000000000000..ce589802a0938d3d4cb8edb4300b9d85d9a85b72
--- /dev/null
+++ b/services/native_viewport/native_viewport_internal.mojom
@@ -0,0 +1,12 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+[DartPackage="native_viewport"]
+module native_viewport;
+
+// Service implemented by the Shell for the Native Viewport service.
+interface NativeViewportShellService {
+  // Asks the shell to create a new native window (on Android, a new task).
+  CreateNewNativeWindow();
+};