exo: Implement notification surface support

components/exo/notification_surface.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.h"
+
+#include "components/exo/notification_surface_registry.h"
+#include "components/exo/surface.h"
+
+namespace exo {
+
+NotificationSurface::NotificationSurface(Surface* surface,
+                                         const std::string& notification_id)
+    : surface_(surface), notification_id_(notification_id) {
+  surface_->AddSurfaceObserver(this);
+  NotificationSurfaceRegistry::Get()->AddSurface(this);
+}
+
+NotificationSurface::~NotificationSurface() {
+  if (surface_)
+    surface_->RemoveSurfaceObserver(this);
+  NotificationSurfaceRegistry::Get()->RemoveSurface(this);
+}
+
+gfx::Size NotificationSurface::GetSize() const {
+  return surface_->GetHitTestBounds().size();

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

Why hit test bounds and not the contents size?

[xiyuan, 2016/06/20 22:40:28]

Did not notice we added a content_size(). Use it now.

+}
+
+void NotificationSurface::OnSurfaceDestroying(Surface* surface) {
+  surface->RemoveSurfaceObserver(this);
+  surface_ = nullptr;
+}
+
+}  // namespace exo