Adds AnimationContainer, which can be used to group a set of

app/animation_container.cc

Index: app/animation_container.cc
diff --git a/app/animation_container.cc b/app/animation_container.cc
new file mode 100644
index 0000000000000000000000000000000000000000..b0cc86a8271fbf7db66df124fdc063cbb28e1c71
--- /dev/null
+++ b/app/animation_container.cc
@@ -0,0 +1,93 @@
+// Copyright (c) 2010 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 "app/animation_container.h"
+
+#include "app/animation.h"
+
+using base::TimeDelta;
+using base::TimeTicks;
+
+AnimationContainer::AnimationContainer()
+    : last_tick_time_(TimeTicks::Now()),
+      observer_(NULL) {
+}
+
+AnimationContainer::~AnimationContainer() {
+  // The animations own us and stop themselves before being deleted. If
+  // animations_ is not empty, something is wrong.
+  DCHECK(animations_.empty());
+}
+
+void AnimationContainer::Start(Animation* animation) {
+  DCHECK(animations_.count(animation) == 0);  // Start should only be invoked
+                                              // if the animation isn't running.
+
+  if (animations_.empty()) {
+    last_tick_time_ = TimeTicks::Now();
+    SetMinTimerInterval(animation->timer_interval());
+  } else if (animation->timer_interval() < min_timer_interval_) {
+    SetMinTimerInterval(animation->timer_interval());
+  }
+
+  animation->set_start_time(last_tick_time_);
+  animations_.insert(animation);
+}
+
+void AnimationContainer::Stop(Animation* animation) {
+  DCHECK(animations_.count(animation) > 0);  // The animation must be running.
+
+  animations_.erase(animation);
+
+  if (animations_.empty()) {
+    timer_.Stop();
+    if (observer_)
+      observer_->AnimationContainerEmpty(this);
+  } else {
+    TimeDelta min_timer_interval = GetMinInterval();
+    if (min_timer_interval > min_timer_interval_)
+      SetMinTimerInterval(min_timer_interval);
+  }
+}
+
+void AnimationContainer::Run() {
+  TimeTicks current_time = TimeTicks::Now();
+
+  last_tick_time_ = current_time;
+
+  // Make a copy of the animations to iterate over so that if any animations
+  // are removed as part of invoking Step there aren't any problems.
+  Animations animations = animations_;
+
+  for (Animations::const_iterator i = animations.begin();
+       i != animations.end(); ++i) {
+    // Make sure the animation is still valid.
+    if (animations_.find(*i) != animations_.end())
+      (*i)->Step(current_time);
+  }
+
+  if (observer_)
+    observer_->AnimationContainerProgressed(this);
+}
+
+void AnimationContainer::SetMinTimerInterval(base::TimeDelta delta) {
+  // This doesn't take into account how far along current animation is, but that
+  // shouldn't be a problem for uses of Animation/AnimationContainer.
+  timer_.Stop();
+  min_timer_interval_ = delta;
+  timer_.Start(min_timer_interval_, this, &AnimationContainer::Run);
+}
+
+TimeDelta AnimationContainer::GetMinInterval() {
+  DCHECK(!animations_.empty());
+
+  TimeDelta min;
+  Animations::const_iterator i = animations_.begin();
+  min = (*i)->timer_interval();
+  for (++i; i != animations_.end(); ++i) {
+    if ((*i)->timer_interval() < min)
+      min = (*i)->timer_interval();
+  }
+  return min;
+}