Implement the Notification `timestamp` property

chrome/android/javatests/src/org/chromium/chrome/browser/notifications/NotificationUIManagerTest.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.notifications;
 
 import static org.chromium.base.test.util.ScalableTimeout.scaleTimeout;
 
 import android.annotation.SuppressLint;
 import android.app.Notification;
@@ skipping 147 matching lines @@
         assertEquals("MyNotification", notification.extras.getString(Notification.EXTRA_TITLE));
         assertEquals("Hello", notification.extras.getString(Notification.EXTRA_TEXT));
         assertEquals(getOrigin(), notification.extras.getString(Notification.EXTRA_SUB_TEXT));
 
         // Verify that the ticker text contains the notification's title and body.
         String tickerText = notification.tickerText.toString();
 
         assertTrue(tickerText.contains("MyNotification"));
         assertTrue(tickerText.contains("Hello"));
 
+        // Verify that the notification's timestamp is set in the past 30 seconds. This number has
+        // no significance, but needs to be high enough to not cause flakiness as it's set by the
+        // renderer process on notification creation.
+        assertTrue((System.currentTimeMillis() - notification.when) < 30 * 1000);

[johnme, 2015/10/20 17:12:20]

Is it worth throwing in a Math.abs just in case the renderer's clock is running
fast (e.g. if the machine synced to a NTP server in between)?

[Peter Beverloo, 2016/01/28 17:18:29]

Done.

+
         // Validate the appearance style of the notification. The EXTRA_TEMPLATE was inroduced
         // in Android Lollipop, we cannot verify this in earlier versions.
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
             assertEquals("android.app.Notification$BigTextStyle",
                     notification.extras.getString(Notification.EXTRA_TEMPLATE));
         }
 
         assertNotNull(notification.largeIcon);
 
         // Validate the notification's behavior.
@@ skipping 280 matching lines @@
      * Verifies that the makeVibrationPattern method returns vibration pattern used
      * in Android notification.
      */
     @SmallTest
     @Feature({"Browser", "Notifications"})
     public void testMakeVibrationPattern() throws Exception {
         assertTrue(Arrays.equals(new long[] {0, 100, 200, 300},
                 NotificationUIManager.makeVibrationPattern(new int[] {100, 200, 300})));
     }
 }