mus: Add debug key to print the server window hierarchy

components/mus/ws/window_manager_state.cc

 // Copyright 2016 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/ws/window_manager_state.h"
 
 #include "base/memory/weak_ptr.h"
 #include "components/mus/ws/accelerator.h"
 #include "components/mus/ws/display_manager.h"
 #include "components/mus/ws/platform_display.h"
@@ skipping 196 matching lines @@
 void WindowManagerState::Deactivate() {
   root_->SetVisible(false);
   event_dispatcher_.Reset();
   // The tree is no longer active, so no point in dispatching any further
   // events.
   std::queue<std::unique_ptr<QueuedEvent>> event_queue;
   event_queue.swap(event_queue_);
 }
 
 void WindowManagerState::ProcessEvent(const ui::Event& event) {
+  RunDebugShortcuts(event);
+
   // If this is still waiting for an ack from a previously sent event, then
   // queue up the event to be dispatched once the ack is received.
   if (event_ack_timer_.IsRunning()) {
     if (!event_queue_.empty() && !event_queue_.back()->processed_target &&
         EventsCanBeCoalesced(*event_queue_.back()->event, event)) {
       event_queue_.back()->event = CoalesceEvents(
           std::move(event_queue_.back()->event), ui::Event::Clone(event));
       return;
     }
     QueueEvent(event, nullptr);
@@ skipping 102 matching lines @@
     event_awaiting_input_ack_ = ui::Event::Clone(event);
     post_target_accelerator_ = accelerator;
   }
 
   // Ignore |tree| because it will receive the event via normal dispatch.
   window_server()->SendToEventObservers(event, user_id_, tree);
 
   tree->DispatchInputEvent(target, event);
 }
 
+void WindowManagerState::RunDebugShortcuts(const ui::Event& event) {

[msw, 2016/05/05 22:12:08]

Should this instead use accelerators, like ash/accelerators/debug_commands.h?
(even if it differs a bit, using accelerators seem more fitting here)

[James Cook, 2016/05/05 22:53:18]

It seems like overkill. Ash already has an accelerator registry, accelerator
dispatch code, etc. In mash, only the window manager has any of that, not the
window server. I doubt the window server itself will handle any shortcuts in
production. It seemed like overkill to build it just for debug stuff.

[msw, 2016/05/05 23:10:06]

See if it's easy to add an accelerator to the EventDispatcher for which this is
a delegate, and then handle it in OnAccelerator. If it's tough, this is fine.

+#if !defined(NDEBUG)
+  if (event.type() != ui::ET_KEY_PRESSED)
+    return;
+  const ui::KeyEvent* key = event.AsKeyEvent();
+  if (key->key_code() == ui::VKEY_S && key->IsControlDown()
+      && key->IsShiftDown() && key->IsAltDown()) {
+    // Error so it will be collected in system logs.
+    LOG(ERROR) << "ServerWindow hierarchy:\n"
+               << root()->GetDebugWindowHierarchy();
+  }
+#endif
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // EventDispatcherDelegate:
 
 void WindowManagerState::OnAccelerator(uint32_t accelerator_id,
                                        const ui::Event& event) {
   DCHECK(IsActive());
   tree_->OnAccelerator(accelerator_id, event);
 }
 
 void WindowManagerState::SetFocusedWindowFromEventDispatcher(
@@ skipping 46 matching lines @@
                                  weak_accelerator);
 }
 
 void WindowManagerState::OnEventTargetNotFound(const ui::Event& event) {
   window_server()->SendToEventObservers(event, user_id_,
                                         nullptr /* ignore_tree */);
 }
 
 }  // namespace ws
 }  // namespace mus