Ash: Implement Toasts

ash/system/toast/toast_manager.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 "ash/system/toast/toast_manager.h"
+
+#include "base/bind.h"
+#include "base/location.h"
+#include "base/thread_task_runner_handle.h"
+
+namespace ash {
+
+namespace {
+
+// Minimum duration for a toast to be visible (in millisecond).
+uint64_t kMinimumDurationMs = 200;
+}
+
+// static
+ToastManager* ToastManager::GetInstance() {
+  // This instance doesn't need to be cleaned up at exit.
+  return base::Singleton<ToastManager,
+                         base::LeakySingletonTraits<ToastManager>>::get();
+}
+
+// private ctor
+ToastManager::ToastManager() {}
+
+ToastManager::~ToastManager() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+}
+
+void ToastManager::Show(const std::string& text, uint64_t duration_ms) {
+  queue_.emplace(std::make_pair(text, duration_ms));
+
+  if (queue_.size() == 1 && overlay_ == nullptr)
+    ShowLatest();
+}
+
+void ToastManager::OnClosed() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+
+  overlay_.reset();
+
+  // Show the next toast if available.
+  if (queue_.size() != 0)
+    ShowLatest();
+}
+
+void ToastManager::ShowLatest() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(!overlay_);
+
+  auto data = queue_.front();
+  uint64_t duration_ms = std::max(data.second, kMinimumDurationMs);
+
+  toast_id_++;
+
+  overlay_.reset(new ToastOverlay(this, data.first /* text */));
+  overlay_->Show(true);
+
+  base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(

[oshima, 2016/03/11 02:06:29]

Won't the posted task outlive ash?

[yoshiki, 2016/03/11 08:40:56]

Done. Now, Ash::Shell has an instance.

+      FROM_HERE,
+      base::Bind(&ToastManager::OnDurationPassed,
+                 base::Unretained(this),  // |this| is never destroyed.
+                 toast_id_),
+      base::TimeDelta::FromMilliseconds(duration_ms));
+
+  queue_.pop();
+}
+
+void ToastManager::OnDurationPassed(int toast_id) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+
+  if (overlay_ && toast_id_ == toast_id)
+    overlay_->Show(false);
+}
+
+}  // namespace ash