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

app/animation_container.h

Index: app/animation_container.h
diff --git a/app/animation_container.h b/app/animation_container.h
new file mode 100644
index 0000000000000000000000000000000000000000..fcb3fadd3b6eb72f9c5c07e34f14831d8c573676
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+++ b/app/animation_container.h
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+// 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.
+
+#ifndef APP_ANIMATION_CONTAINER_H_
+#define APP_ANIMATION_CONTAINER_H_
+
+#include <set>
+
+#include "base/ref_counted.h"
+#include "base/time.h"
+#include "base/timer.h"
+
+class Animation;
+
+// AnimationContainer is used by Animation to manage the underlying timer.
+// Internally each Animation creates a single AnimationContainer. You can
+// group a set of Animations into the same AnimationContainer by way of
+// Animation::SetContainer. Grouping a set of Animations into the same
+// AnimationContainer ensures they all update and start at the same time.
+//
+// AnimationContainer is ref counted. Each Animation contained within the
+// AnimationContainer own it.
+class AnimationContainer : public base::RefCounted<AnimationContainer> {
+ public:
+  // The observer is notified after every update of the animations managed by
+  // the container.
+  class Observer {
+   public:
+    // Invoked on every tick of the timer managed by the container and after
+    // all the animations have updated.
+    virtual void AnimationContainerProgressed(
+        AnimationContainer* container) = 0;
+
+    // Invoked when no more animations are being managed by this container.
+    virtual void AnimationContainerEmpty(AnimationContainer* container) = 0;
+  };
+
+  AnimationContainer();
+
+  void set_observer(Observer* observer) { observer_ = observer; }
+
+  // The time the last animation ran at.
+  base::TimeTicks last_tick_time() const { return last_tick_time_; }
+
+  // Are there any timers running?
+  bool is_running() const { return !animations_.empty(); }
+
+ private:
+  friend class Animation;
+  friend class base::RefCounted<AnimationContainer>;
+
+  typedef std::set<Animation*> Animations;
+
+  ~AnimationContainer();
+
+  // Invoked by Animation when it needs to start. Starts the timer if necessary.
+  void Start(Animation* animation);
+
+  // Invoked by Animation when it needs to stop. If there are no more animations
+  // running the timer stops.
+  void Stop(Animation* animation);
+
+  // Timer callback method.
+  void Run();
+
+  // Sets min_timer_interval_ and restarts the timer.
+  void SetMinTimerInterval(base::TimeDelta delta);
+
+  // Returns the min timer interval of all the timers.
+  base::TimeDelta GetMinInterval();
+
+  // Represents one of two possible values:
+  // . If only a single animation has been started and the timer hasn't yet
+  //   fired this is the time the animation was added.
+  // . The time the last animation ran at (::Run was invoked).
+  base::TimeTicks last_tick_time_;
+
+  // Set of animations being managed.
+  Animations animations_;
+
+  // Minimum interval the timers run at.
+  base::TimeDelta min_timer_interval_;
+
+  base::RepeatingTimer<AnimationContainer> timer_;
+
+  Observer* observer_;
+
+  DISALLOW_COPY_AND_ASSIGN(AnimationContainer);
+};
+
+#endif  // APP_ANIMATION_CONTAINER_H_