cc: Add UniqueNotifier to cc/base.

cc/base/unique_notifier.cc

+// Copyright 2014 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 "cc/base/unique_notifier.h"
+
+#include "base/bind.h"
+#include "base/bind_helpers.h"
+#include "base/location.h"
+#include "base/sequenced_task_runner.h"
+
+namespace cc {
+
+UniqueNotifier::UniqueNotifier(
+    const scoped_refptr<base::SequencedTaskRunner>& task_runner,
+    const base::Closure& closure,
+    const base::TimeDelta& delay)
+    : task_runner_(task_runner),
+      closure_(closure),
+      delay_(delay),
+      notification_pending_(false),
+      weak_ptr_factory_(this) {
+}
+
+UniqueNotifier::~UniqueNotifier() {
+  weak_ptr_factory_.InvalidateWeakPtrs();

[reveman, 2014/05/21 17:03:37]

No need to do this explicitly. I think it's pretty clear that this will happen
implicitly. 

[vmpstr, 2014/05/21 17:41:02]

Done.

+}
+
+void UniqueNotifier::Schedule() {
+  if (notification_pending_) {
+    if (delay_ != base::TimeDelta())
+      next_notification_time_ = base::TimeTicks::Now() + delay_;
+    return;
+  }
+
+  if (delay_ == base::TimeDelta()) {
+    task_runner_->PostTask(FROM_HERE,
+                           base::Bind(&UniqueNotifier::NotifyIfTime,
+                                      weak_ptr_factory_.GetWeakPtr()));
+  } else {
+    next_notification_time_ = base::TimeTicks::Now() + delay_;
+    task_runner_->PostDelayedTask(FROM_HERE,
+                                  base::Bind(&UniqueNotifier::NotifyIfTime,
+                                             weak_ptr_factory_.GetWeakPtr()),
+                                  delay_);
+  }
+  notification_pending_ = true;
+}
+
+void UniqueNotifier::NotifyIfTime() {
+  if (!next_notification_time_.is_null()) {
+    base::TimeTicks now = base::TimeTicks::Now();
+    if (next_notification_time_ > now) {
+      task_runner_->PostDelayedTask(FROM_HERE,
+                                    base::Bind(&UniqueNotifier::NotifyIfTime,
+                                               weak_ptr_factory_.GetWeakPtr()),
+                                    next_notification_time_ - now);
+      return;
+    }
+  }
+
+  notification_pending_ = false;
+  closure_.Run();
+}
+
+}  // namespace cc