compositor: Tick the UI animations from cc, instead of from timer callbacks.

ui/compositor/layer_animator_collection.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 "ui/compositor/layer_animator_collection.h"
+
+#include <set>
+
+#include "base/lazy_instance.h"
+#include "base/time/time.h"
+#include "ui/compositor/layer_animator.h"
+#include "ui/gfx/frame_time.h"
+
+namespace ui {
+
+namespace {
+
+base::LazyInstance<LayerAnimatorCollection>::Leaky g_lazy_instance;
+}
+
+// static
+LayerAnimatorCollection* LayerAnimatorCollection::GetInstance() {
+  return g_lazy_instance.Pointer();
+}
+
+void LayerAnimatorCollection::StartAnimator(
+    scoped_refptr<LayerAnimator> animator) {
+  if (!animators_.size())
+    last_tick_time_ = gfx::FrameTime::Now();
+  animators_.insert(animator);
+}
+
+void LayerAnimatorCollection::StopAnimator(
+    scoped_refptr<LayerAnimator> animator) {
+  DCHECK_GT(animators_.count(animator), 0U);
+  animators_.erase(animator);
+}
+
+bool LayerAnimatorCollection::HasActiveAnimators() const {
+  return !animators_.empty();
+}
+
+void LayerAnimatorCollection::Progress(base::TimeTicks now) {
+  std::set<scoped_refptr<LayerAnimator> > list = animators_;
+  for (std::set<scoped_refptr<LayerAnimator> >::iterator iter = list.begin();
+       iter != list.end();
+       ++iter) {
+    // Make sure the animator is still valid.
+    if (animators_.count(*iter) > 0)
+      (*iter)->Step(now);
+  }
+  last_tick_time_ = now;
+}
+
+// private:
+LayerAnimatorCollection::LayerAnimatorCollection()
+    : last_tick_time_(gfx::FrameTime::Now()) {
+}
+
+LayerAnimatorCollection::~LayerAnimatorCollection() {
+}
+
+}  // namespace ui