Added a CallbackLayerAnimationObserver.

ui/compositor/callback_layer_animation_observer.cc

Index: ui/compositor/callback_layer_animation_observer.cc
diff --git a/ui/compositor/callback_layer_animation_observer.cc b/ui/compositor/callback_layer_animation_observer.cc
new file mode 100644
index 0000000000000000000000000000000000000000..305bce6a700ee1f78dd7bcc8f896a90ded07b1df
--- /dev/null
+++ b/ui/compositor/callback_layer_animation_observer.cc
@@ -0,0 +1,115 @@
+// 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 "ui/compositor/callback_layer_animation_observer.h"
+
+#include "ui/compositor/layer_animation_sequence.h"
+
+namespace ui {
+
+CallbackLayerAnimationObserver::CallbackLayerAnimationObserver(
+    AnimationStartedCallback animation_started_callback,
+    AnimationEndedCallback animation_ended_callback)
+    : active_(false),
+      attached_sequence_count_(0),
+      detached_sequence_count_(0),
+      started_count_(0),
+      aborted_count_(0),
+      successful_count_(0),
+      animation_started_callback_(animation_started_callback),
+      animation_ended_callback_(animation_ended_callback),
+      destroyed_(nullptr) {}
+
+CallbackLayerAnimationObserver::~CallbackLayerAnimationObserver() {
+  if (destroyed_)
+    *destroyed_ = true;
+}
+
+void CallbackLayerAnimationObserver::SetActive() {
+  active_ = true;
+
+  bool destroyed = false;
+  destroyed_ = &destroyed;
+
+  CheckAllSequencesStarted();
+
+  if (destroyed)
+    return;
+  destroyed_ = nullptr;
+
+  CheckAllSequencesCompleted();
+}
+
+void CallbackLayerAnimationObserver::OnLayerAnimationStarted(
+    ui::LayerAnimationSequence* sequence) {
+  CHECK_LT(started_count_, attached_sequence_count_);
+  ++started_count_;
+  CheckAllSequencesStarted();
+}
+
+void CallbackLayerAnimationObserver::OnLayerAnimationEnded(
+    ui::LayerAnimationSequence* sequence) {
+  CHECK_LT(GetNumSequencesCompleted(), attached_sequence_count_);
+  ++successful_count_;
+  CheckAllSequencesCompleted();
+}
+
+void CallbackLayerAnimationObserver::OnLayerAnimationAborted(
+    ui::LayerAnimationSequence* sequence) {
+  CHECK_LT(GetNumSequencesCompleted(), attached_sequence_count_);
+  ++aborted_count_;
+  CheckAllSequencesCompleted();
+}
+
+void CallbackLayerAnimationObserver::OnLayerAnimationScheduled(
+    ui::LayerAnimationSequence* sequence) {}
+
+bool CallbackLayerAnimationObserver::RequiresNotificationWhenAnimatorDestroyed()
+    const {
+  return true;
+}
+
+void CallbackLayerAnimationObserver::OnAttachedToSequence(
+    ui::LayerAnimationSequence* sequence) {
+  ++attached_sequence_count_;
+}
+
+void CallbackLayerAnimationObserver::OnDetachedFromSequence(
+    ui::LayerAnimationSequence* sequence) {
+  CHECK_LT(detached_sequence_count_, attached_sequence_count_);
+  ++detached_sequence_count_;
+}
+
+int CallbackLayerAnimationObserver::GetNumSequencesCompleted() {
+  return aborted_count_ + successful_count_;
+}
+
+void CallbackLayerAnimationObserver::CheckAllSequencesStarted() {
+  if (active_ && attached_sequence_count_ == started_count_)
+    animation_started_callback_.Run(*this);
+}
+
+void CallbackLayerAnimationObserver::CheckAllSequencesCompleted() {
+  if (active_ && GetNumSequencesCompleted() == attached_sequence_count_) {
+    active_ = false;
+    bool destroyed = false;
+    destroyed_ = &destroyed;
+
+    bool should_delete = animation_ended_callback_.Run(*this);
+
+    if (destroyed) {
+      if (should_delete)
+        LOG(WARNING) << "CallbackLayerAnimationObserver was explicitly "
+                        "destroyed AND was requested to be destroyed via the "
+                        "AnimationEndedCallback's return value.";
+      return;
+    }
+    destroyed_ = nullptr;
+
+    if (should_delete)
+      delete this;
+  }
+}
+
+}  // namespace ui