Upstream oodles of Chrome for Android code into Chromium.

chrome/android/java_staging/src/org/chromium/chrome/browser/compositor/Invalidator.java

+// Copyright 2015 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.compositor;
+
+/**
+ * The {@link Invalidator} invalidates a client when it is the right time.
+ */
+public class Invalidator {
+    /**
+     * Interface for the client that gets invalidated.
+     */
+    public interface Client {
+        /**
+         * Do the invalidation.
+         */
+        void doInvalidate();
+    }
+
+    /**
+     * Interface for the host that drives the invalidations.
+     */
+    public interface Host {
+        /**
+         * Requests an invalidation of the view.
+         *
+         * @param view The {@link View} to invalidate.
+         */
+        void deferInvalidate(Client view);
+    }
+
+    private Host mHost;
+
+    /**
+     * @param host The invalidator host, responsible for invalidating views.
+     */
+    public void set(Host host) {
+        mHost = host;
+    }
+
+    /**
+     * Invalidates either immediately (if no host is specified) or at time
+     * triggered by the host.
+     *
+     * @param client The {@link Client} to invalidate, most likely a view.
+     */
+    public void invalidate(Client client) {
+        if (mHost != null) {
+            mHost.deferInvalidate(client);
+        } else {
+            client.doInvalidate();
+        }
+    }
+}