aura-mus: create an interactive ui test for drag and drop.

ui/aura/mus/window_tree_client.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 "ui/aura/mus/window_tree_client.h"
 
 #include <stddef.h>
 
 #include <string>
 #include <utility>
@@ skipping 463 matching lines @@
       gfx::ConvertRectToDIP(ScaleFactorForDisplay(window), window_data.bounds));
   if (parent)
     parent->AddChildFromServer(window_port_mus_ptr);
   if (window_data.visible)
     window_mus->SetVisibleFromServer(true);
   return window_port_mus_ptr;
 }
 
 void WindowTreeClient::SetWindowTree(ui::mojom::WindowTreePtr window_tree_ptr) {
   tree_ptr_ = std::move(window_tree_ptr);
+
+  // Enable nested dispatch on both sides of this connect because these objects
+  // are used in the presence of nested runloops, such as those during drag and
+  // drop.
+  binding_.EnableNestedDispatch(true);
+  tree_ptr_.EnableNestedDispatch(true);
+
   WindowTreeConnectionEstablished(tree_ptr_.get());
   tree_ptr_->GetCursorLocationMemory(
       base::Bind(&WindowTreeClient::OnReceivedCursorLocationMemory,
                  weak_factory_.GetWeakPtr()));
 
   tree_ptr_.set_connection_error_handler(base::Bind(
       &WindowTreeClient::OnConnectionLost, weak_factory_.GetWeakPtr()));
 
   if (window_manager_delegate_) {
     tree_ptr_->GetWindowManagerClient(
@@ skipping 892 matching lines @@
     gfx::Rect bounds_in_dip = transit_bounds_in_dip;
     // TODO: this needs to trigger scheduling a bounds change on |window|.
     result = window_manager_delegate_->OnWmSetBounds(window->GetWindow(),
                                                      &bounds_in_dip);
     if (result) {
       // If the resulting bounds differ return false. Returning false ensures
       // the client applies the bounds we set below.
       result = bounds_in_dip == transit_bounds_in_dip;
       window->SetBoundsFromServer(bounds_in_dip);
     }
+  } else {
+    DVLOG(1) << "Bad window passed to WmSetBounds().";

[sky, 2017/03/17 00:02:21]

Bad -> Unknown (just because it's possible the client deleted the window and bad
makes it sound, well, bad).

[Elliot Glaysher, 2017/03/17 17:43:12]

Done.

   }
   if (window_manager_internal_client_)
     window_manager_internal_client_->WmResponse(change_id, result);
 }
 
 void WindowTreeClient::WmSetProperty(
     uint32_t change_id,
     Id window_id,
     const std::string& name,
     const base::Optional<std::vector<uint8_t>>& transit_data) {
@@ skipping 443 matching lines @@
   return ScheduleInFlightChange(base::MakeUnique<InFlightCaptureChange>(
       this, capture_synchronizer_.get(), window));
 }
 
 uint32_t WindowTreeClient::CreateChangeIdForFocus(WindowMus* window) {
   return ScheduleInFlightChange(base::MakeUnique<InFlightFocusChange>(
       this, focus_synchronizer_.get(), window));
 }
 
 }  // namespace aura