Update WindowTree::OnWindowInputEventAck to include handled

components/mus/public/cpp/lib/window_tree_client_impl.cc

 // Copyright 2014 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.
 
 #include "components/mus/public/cpp/lib/window_tree_client_impl.h"
 
 #include <stddef.h>
 #include <utility>
 
 #include "base/bind.h"
@@ skipping 802 matching lines @@
     return;
 
   WindowPrivate(window).LocalSetSharedProperty(name, std::move(new_data));
 }
 
 void WindowTreeClientImpl::OnWindowInputEvent(uint32_t event_id,
                                               Id window_id,
                                               mojom::EventPtr event) {
   Window* window = GetWindowById(window_id);
   if (!window || !window->input_event_handler_) {
-    tree_->OnWindowInputEventAck(event_id);
+    tree_->OnWindowInputEventAck(event_id, false);
     return;
   }
 
-  scoped_ptr<base::Closure> ack_callback(
-      new base::Closure(base::Bind(&mojom::WindowTree::OnWindowInputEventAck,
-                                   base::Unretained(tree_), event_id)));
+  scoped_ptr<base::Callback<void(bool)>> ack_callback(
+      new base::Callback<void(bool)>(
+          base::Bind(&mojom::WindowTree::OnWindowInputEventAck,
+                     base::Unretained(tree_), event_id)));
   window->input_event_handler_->OnWindowInputEvent(window, std::move(event),
                                                    &ack_callback);
   if (ack_callback)
-    ack_callback->Run();
+    ack_callback->Run(false);

[sky, 2016/03/01 23:08:17]

Why does this supply false?

[jonross, 2016/03/01 23:26:16]

There is an undocumented expectation on:
  window->input_event_handler_->OnWindowInputEvent
That if the call location acks the event that it clears the scoped_ptr.

This call is a fallback to make sure the server gets an ack for the event in
case the handler didn't ack. I went with false, as an input_event_handler should
ack with 'true' if handled.

I could document this expectation, or it might be be more clearer if
OnWindowInputEvent returned a bool for if it sent an ack.

 }
 
 void WindowTreeClientImpl::OnWindowFocused(Id focused_window_id) {
   Window* focused_window = GetWindowById(focused_window_id);
   InFlightFocusChange new_change(this, focused_window);
   if (ApplyServerChangeToExistingInFlightChange(new_change))
     return;
 
   LocalSetFocus(focused_window);
 }
@@ skipping 135 matching lines @@
 
 void WindowTreeClientImpl::SetUnderlaySurfaceOffsetAndExtendedHitArea(
     Window* window,
     const gfx::Vector2d& offset,
     const gfx::Insets& hit_area) {
   window_manager_internal_client_->SetUnderlaySurfaceOffsetAndExtendedHitArea(
       window->id(), offset.x(), offset.y(), mojo::Insets::From(hit_area));
 }
 
 }  // namespace mus