Make Mozart view manager use the new compositor.

mojo/services/ui/input/interfaces/input_dispatcher.mojom

Index: mojo/services/ui/input/interfaces/input_dispatcher.mojom
diff --git a/mojo/services/ui/input/interfaces/input_dispatcher.mojom b/mojo/services/ui/input/interfaces/input_dispatcher.mojom
new file mode 100644
index 0000000000000000000000000000000000000000..75caef51fbfd8162e403be3f6d5978c9380db9d6
--- /dev/null
+++ b/mojo/services/ui/input/interfaces/input_dispatcher.mojom
@@ -0,0 +1,40 @@
+// 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="mojo_services"]
+module mojo.ui;
+
+// TODO(jeffbrown): Redesign input event representation later.
+import "mojo/services/input_events/interfaces/input_events.mojom";
+
+// The input dispatcher service allows the component which owns and controls
+// a view tree to dispatch input events to the views that it contains.
+//
+// This service can be retrieved from the |ViewTreeHost| service provider.
+//
+// TODO(jeffbrown): Elaborate how input devices are registered with the
+// dispatcher so that applications can query their capabilities and distinguish
+// input coming from multiple sources concurrently.
+[ServiceName="mojo::ui::InputDispatcher"]
+interface InputDispatcher {
+  // Dispatches an event through the view tree.  The dispatcher will deliver
+  // the event to the appropriate views based on the current state of the
+  // tree, such as focus and the structure of the scene graph.
+  //
+  // The dispatcher expects the stream of events that it receives to be
+  // internally consistent.  For example, each pointer down must be matched
+  // by a corresponding pointer up.
+  //
+  // It is an error to supply an inconsistent stream events to the dispatcher;
+  // the connection will be closed.
+  //
+  // TODO(jeffbrown): Is this the right policy?  It would certainly help
+  // diagnose faults earlier.
+  // TODO(jeffbrown): Decide whether there should be a way to track the
+  // progress of input events.  For testing purposes it is often desirable
+  // to block the test until a sequence of events have been delivered and
+  // handled.  However these same mechanisms have proven to be brittle in
+  // the past so it might be better to solve the problem some other way.
+  DispatchEvent(mojo.Event event);

[abarth, 2016/01/10 01:42:54]

I guess it's up to the InputDispatcher to decide who to dispatch the event to
(and in what order)?

[jeffbrown, 2016/01/26 05:59:12]

Yup.  It owns all of the policy, this is just the entry point for events coming
into the system.

+};