aura-mus: Make StackAtTop() proxy to the window manager.

ui/aura/mus/window_tree_client.cc

Index: ui/aura/mus/window_tree_client.cc
diff --git a/ui/aura/mus/window_tree_client.cc b/ui/aura/mus/window_tree_client.cc
index d5cef1fae1c448b7cc621187bf7ab32de56a5eb9..150ea7a40ceeb18db1243d0ce63e7a0827e58ba2 100644
--- a/ui/aura/mus/window_tree_client.cc
+++ b/ui/aura/mus/window_tree_client.cc
@@ -1325,6 +1325,15 @@ void WindowTreeClient::OnChangeCompleted(uint32_t change_id, bool success) {
     on_current_move_finished_.Run(success);
     on_current_move_finished_.Reset();
   }
+
+  // Look for a corresponding window manager change in the
+  if (window_manager_internal_client_) {
+    auto it = in_flight_change_map_.find(change_id);
+    if (it != in_flight_change_map_.end()) {
+      window_manager_internal_client_->WmResponse(it->second, success);
+      in_flight_change_map_.erase(it);
+    }
+  }
 }
 
 void WindowTreeClient::GetWindowManager(
@@ -1510,6 +1519,34 @@ void WindowTreeClient::WmDeactivateWindow(Id window_id) {
   window_manager_delegate_->OnWmDeactivateWindow(window->GetWindow());
 }
 
+void WindowTreeClient::WmStackAtTop(uint32_t wm_change_id, uint32_t window_id) {
+  WindowMus* window = GetWindowByServerId(window_id);

[sky, 2017/01/24 17:18:23]

I think you want almost the same logic here as is in OnWindowMusMoveChild. In
fact if you call StackAtTop from this implementation I think it'll generate
everything you need. The only additional call you need id the WmResponse call.

+  if (!window) {
+    DVLOG(1) << "Attempt to stack at top invalid window " << window_id;
+    if (window_manager_internal_client_)
+      window_manager_internal_client_->WmResponse(wm_change_id, false);
+    return;
+  }
+
+  Window* parent = window->GetWindow()->parent();
+  WindowMus* relative_window = WindowMus::Get(parent->children().back());
+  if (relative_window == window) {
+    DVLOG(3) << "WmStackAtTop ignored (already at top)";
+    if (window_manager_internal_client_)
+      window_manager_internal_client_->WmResponse(wm_change_id, true);
+    return;
+  }
+
+  const uint32_t client_change_id = ScheduleInFlightChange(
+      base::MakeUnique<CrashInFlightChange>(WindowMus::Get(parent),
+                                            ChangeType::REORDER));
+  in_flight_change_map_.insert(std::make_pair(client_change_id, wm_change_id));
+  tree_->ReorderWindow(client_change_id,
+                       window->server_id(),
+                       relative_window->server_id(),
+                       ui::mojom::OrderDirection::ABOVE);
+}
+
 void WindowTreeClient::OnAccelerator(uint32_t ack_id,
                                      uint32_t accelerator_id,
                                      std::unique_ptr<ui::Event> event) {