CancelAwareAnimatorListener and Refactor Custom Tab Toolbar Animation

chrome/android/java/src/org/chromium/chrome/browser/widget/animation/CancelAwareAnimatorListener.java

Index: chrome/android/java/src/org/chromium/chrome/browser/widget/animation/CancelAwareAnimatorListener.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/widget/animation/CancelAwareAnimatorListener.java b/chrome/android/java/src/org/chromium/chrome/browser/widget/animation/CancelAwareAnimatorListener.java
new file mode 100644
index 0000000000000000000000000000000000000000..f8313ab47c0e2c56bc0da03ac9c90762149a285f
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/widget/animation/CancelAwareAnimatorListener.java
@@ -0,0 +1,51 @@
+// Copyright 2016 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.
+
+package org.chromium.chrome.browser.widget.animation;
+
+import android.animation.Animator;
+import android.animation.AnimatorListenerAdapter;
+
+/**
+ * An {@link AnimatorListenerAdapter} that distinguishes cancel and end signal. Subclasses should
+ * override {@link #onStart(Animator)}, {@link #onEnd(Animator)} and {@link #onCancel(Animator)}
+ * instead of the standard callback functions.
+ */
+public class CancelAwareAnimatorListener extends AnimatorListenerAdapter {
+    private boolean mIsCancelled;
+
+    @Override
+    public final void onAnimationStart(Animator animation) {
+        mIsCancelled = false;
+        onStart(animation);
+    }
+
+    @Override
+    public final void onAnimationCancel(Animator animation) {
+        mIsCancelled = true;
+        onCancel(animation);
+    }
+
+    @Override
+    public final void onAnimationEnd(Animator animation) {
+        if (mIsCancelled) return;
+        onEnd(animation);
+    }
+
+    /**
+     * Notifies the start of the animator.
+     */
+    public void onStart(Animator animator) { }
+
+    /**
+     * Notifies that the animator was cancelled.
+     */
+    public void onCancel(Animator animator) { }
+
+    /**
+     * Notifies that the animator has finished running. This method will not be called if the
+     * animator is canclled.
+     */
+    public void onEnd(Animator animator) { }
+}