Add support for highlighting menu items

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

Index: chrome/android/java/src/org/chromium/chrome/browser/appmenu/PulseDrawableFactory.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/appmenu/PulseDrawableFactory.java b/chrome/android/java/src/org/chromium/chrome/browser/appmenu/PulseDrawableFactory.java
new file mode 100644
index 0000000000000000000000000000000000000000..09901038580124ca0607f4237fd2484edb811cae
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/appmenu/PulseDrawableFactory.java
@@ -0,0 +1,70 @@
+// 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.graphics.Canvas;
+import android.graphics.Paint;
+import android.graphics.Rect;
+import android.support.v4.view.animation.FastOutSlowInInterpolator;
+import android.support.v4.view.animation.PathInterpolatorCompat;
+
+import org.chromium.base.ContextUtils;
+import org.chromium.chrome.R;
+import org.chromium.chrome.browser.util.MathUtils;
+
+/**
+ * A helper factory to create {@link PulseDrawable}s.
+ */
+public class PulseDrawableFactory {
+    /**
+     * Creates a {@link PulseDrawable} that will fill the bounds with a pulsing color.
+     * @return A new {@link PulseDrawable} instance.
+     */
+    public static PulseDrawable createHighlight() {

[Ted C, 2017/04/12 18:05:57]

Any reason these aren't statics in PulseDrawable?

Then we could have the constructor be private and these could be the only way
you interact with that class (then you don't have to think about what the
painter is or anything).

[David Trainor- moved to gerrit, 2017/04/12 18:59:37]

Sure sounds good.

+        PulseDrawable.Painter painter = new PulseDrawable.Painter() {
+            @Override
+            public void modifyDrawable(PulseDrawable drawable, float interpolation) {
+                drawable.setAlpha((int) MathUtils.interpolate(12, 75, interpolation));
+            }
+
+            @Override
+            public void draw(
+                    PulseDrawable drawable, Paint paint, Canvas canvas, float interpolation) {
+                canvas.drawRect(drawable.getBounds(), paint);
+            }
+        };
+
+        return new PulseDrawable(ContextUtils.getApplicationContext().getResources(),
+                R.color.google_blue_500, new FastOutSlowInInterpolator(), painter);
+    }
+
+    /**
+     * Creates a {@link PulseDrawable} that will draw a pulsing circle inside the bounds.
+     * @return A new {@link PulseDrawable} instance.
+     */
+    public static PulseDrawable createCircle() {
+        PulseDrawable.Painter painter = new PulseDrawable.Painter() {
+            @Override
+            public void modifyDrawable(PulseDrawable drawable, float interpolation) {
+                drawable.invalidateSelf();
+            }
+
+            @Override
+            public void draw(
+                    PulseDrawable drawable, Paint paint, Canvas canvas, float interpolation) {
+                Rect bounds = drawable.getBounds();
+                float scale = MathUtils.interpolate(0.8f, 1.f, interpolation);
+                float radius = Math.min(bounds.width(), bounds.height()) * scale / 2.f;
+                canvas.drawCircle(bounds.exactCenterX(), bounds.exactCenterY(), radius, paint);
+            }
+        };
+
+        PulseDrawable drawable = new PulseDrawable(
+                ContextUtils.getApplicationContext().getResources(), R.color.google_blue_500,
+                PathInterpolatorCompat.create(.8f, 0.f, .6f, 1.f), painter);
+        drawable.setAlpha(76);
+        return drawable;
+    }
+}