Add support for highlighting menu items

chrome/android/java/src/org/chromium/chrome/browser/appmenu/RowHighlightDrawable.java

Index: chrome/android/java/src/org/chromium/chrome/browser/appmenu/RowHighlightDrawable.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/appmenu/RowHighlightDrawable.java b/chrome/android/java/src/org/chromium/chrome/browser/appmenu/RowHighlightDrawable.java
new file mode 100644
index 0000000000000000000000000000000000000000..14d36c0471d9942c9eca3e3b6b354358d6e606df
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/appmenu/RowHighlightDrawable.java
@@ -0,0 +1,64 @@
+// Copyright 2017 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.appmenu;
+
+import android.animation.Animator;
+import android.animation.AnimatorListenerAdapter;
+import android.animation.AnimatorSet;
+import android.animation.ObjectAnimator;
+import android.graphics.drawable.ColorDrawable;
+import android.support.annotation.ColorInt;
+import android.support.v4.view.animation.FastOutSlowInInterpolator;
+
+/** A {@link Drawable} that pulses a color. */
+public class RowHighlightDrawable extends ColorDrawable {
+    /** Creates a new black pulsing {@link RowHighlightDrawable}. */
+    public RowHighlightDrawable() {
+        startAnimation();
+    }
+
+    /**
+     * Creates a new {@link RowHighlightDrawable} with the specified color.
+     * @param color The color to draw.
+     */
+    public RowHighlightDrawable(@ColorInt int color) {
+        super(color);
+        startAnimation();
+    }
+
+    private void startAnimation() {
+        setAlpha(75);
+        ObjectAnimator fadeInAnim = ObjectAnimator.ofInt(this, "alpha", 75, 12);
+        fadeInAnim.setStartDelay(500);
+        fadeInAnim.setDuration(500);
+        fadeInAnim.setInterpolator(new FastOutSlowInInterpolator());
+
+        ObjectAnimator fadeOutAnim = ObjectAnimator.ofInt(this, "alpha", 12, 75);
+        fadeOutAnim.setDuration(250);
+        fadeOutAnim.setInterpolator(new FastOutSlowInInterpolator());
+
+        AnimatorSet set = new AnimatorSet();
+        set.playSequentially(fadeInAnim, fadeOutAnim);
+        set.addListener(new AnimatorListenerAdapter() {
+            private boolean mCanceled;
+
+            @Override
+            public void onAnimationStart(Animator animation) {
+                mCanceled = false;
+            }
+
+            @Override
+            public void onAnimationCancel(Animator animation) {
+                mCanceled = true;
+            }
+
+            @Override
+            public void onAnimationEnd(Animator animation) {
+                if (!mCanceled) animation.start();
+            }
+        });
+        set.start();
+    }
+}