mus: Notify the client whether adding an accelerator was successful.

components/mus/ws/event_dispatcher.cc

 // 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.
 
 #include "components/mus/ws/event_dispatcher.h"
 
 #include <set>
 
 #include "cc/surfaces/surface_hittest.h"
 #include "components/mus/surfaces/surfaces_state.h"
@@ skipping 91 matching lines @@
     if (fields_to_match_ & POINTER_LOCATION) {
       // TODO(sad): The tricky part here is to make sure the same coord-space is
       // used for the location-region and the event-location.
       NOTIMPLEMENTED();
       return false;
     }
 
     return true;
   }
 
-#if !defined(NDEBUG)
   bool Equals(const EventMatcher& matcher) const {
     return fields_to_match_ == matcher.fields_to_match_ &&
            event_type_ == matcher.event_type_ &&
            event_flags_ == matcher.event_flags_ &&
            keyboard_code_ == matcher.keyboard_code_ &&
            pointer_kind_ == matcher.pointer_kind_ &&
            pointer_region_ == matcher.pointer_region_;
   }
-#endif
 
  private:
   enum MatchFields {
     NONE = 0,
     TYPE = 1 << 0,
     FLAGS = 1 << 1,
     KEYBOARD_CODE = 1 << 2,
     POINTER_KIND = 1 << 3,
     POINTER_LOCATION = 1 << 4,
   };
@@ skipping 14 matching lines @@
 EventDispatcher::~EventDispatcher() {
   std::set<ServerWindow*> pointer_targets;
   for (const auto& pair : pointer_targets_) {
     if (pair.second.window &&
         pointer_targets.insert(pair.second.window).second) {
       pair.second.window->RemoveObserver(this);
     }
   }
 }
 
-void EventDispatcher::AddAccelerator(uint32_t id,
+bool EventDispatcher::AddAccelerator(uint32_t id,
                                      mojom::EventMatcherPtr event_matcher) {
   EventMatcher matcher(*event_matcher);
-#if !defined(NDEBUG)
+  // If an accelerator with the same id or matcher already exists, then abort.
   for (const auto& pair : accelerators_) {
-    DCHECK_NE(pair.first, id);
-    DCHECK(!matcher.Equals(pair.second));
+    if (pair.first == id || matcher.Equals(pair.second))
+      return false;
   }
-#endif
   accelerators_.insert(Entry(id, matcher));
+  return true;
 }
 
 void EventDispatcher::RemoveAccelerator(uint32_t id) {
   auto it = accelerators_.find(id);
   DCHECK(it != accelerators_.end());
   accelerators_.erase(it);
 }
 
 void EventDispatcher::OnEvent(mojom::EventPtr event) {
   if (!root_)
@@ skipping 134 matching lines @@
 void EventDispatcher::OnWindowVisibilityChanged(ServerWindow* window) {
   CancelPointerEventsToTarget(window);
 }
 
 void EventDispatcher::OnWindowDestroyed(ServerWindow* window) {
   CancelPointerEventsToTarget(window);
 }
 
 }  // namespace ws
 }  // namespace mus