exo: Implement notification surface support

components/exo/notification_surface_registry.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/exo/notification_surface_registry.h"
+
+#include <algorithm>
+
+#include "components/exo/notification_surface.h"
+#include "ui/arc/notification/arc_notification_manager.h"
+
+namespace exo {
+
+namespace {
+
+base::LazyInstance<NotificationSurfaceRegistry> instance =
+    LAZY_INSTANCE_INITIALIZER;
+
+}  // namespace
+
+NotificationSurfaceRegistry::NotificationSurfaceRegistry() {}
+
+NotificationSurfaceRegistry::~NotificationSurfaceRegistry() {}
+
+// static
+NotificationSurfaceRegistry* NotificationSurfaceRegistry::Get() {
+  return instance.Pointer();
+}
+
+NotificationSurface* NotificationSurfaceRegistry::GetSurface(
+    const std::string& notification_key) const {
+  auto it = notification_surface_map_.find(notification_key);
+  return it == notification_surface_map_.end() ? nullptr : it->second;
+}
+
+void NotificationSurfaceRegistry::AddSurface(NotificationSurface* surface) {
+  DCHECK(notification_surface_map_.find(surface->notification_id()) ==

[reveman, 2016/06/16 03:35:20]

Can a client cause this to fail? That would be a security issue as clients
should not be able to crash the browser. In that case, this would need to be
validated earlier and handled as an error condition when creating the
notifiction surface.

[xiyuan, 2016/06/20 22:40:29]

Do the check when processing the request. Client should never cause this to
trigger and changed this to NOTREACHED and bail.

+         notification_surface_map_.end());
+
+  notification_surface_map_[surface->notification_id()] = surface;
+
+  FOR_EACH_OBSERVER(Observer, observers_, OnNotificationSurfaceAdded(surface));
+}
+
+void NotificationSurfaceRegistry::RemoveSurface(NotificationSurface* surface) {
+  auto it = notification_surface_map_.find(surface->notification_id());
+  if (it == notification_surface_map_.end())
+    return;
+
+  notification_surface_map_.erase(it);
+  FOR_EACH_OBSERVER(Observer, observers_,
+                    OnNotificationSurfaceRemoved(surface));
+}
+
+void NotificationSurfaceRegistry::AddObserver(Observer* observer) {
+  observers_.AddObserver(observer);
+}
+
+void NotificationSurfaceRegistry::RemoveObserver(Observer* observer) {
+  observers_.RemoveObserver(observer);
+}
+
+}  // namespace exo