Performs saftey schedule of another task in BackgroundOfflinerTask in case processing killed

chrome/android/java/src/org/chromium/chrome/browser/offlinepages/BackgroundOfflinerTask.java

 // 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.offlinepages;
 
 import android.content.Context;
 import android.os.Bundle;
 
 import org.chromium.base.Callback;
 import org.chromium.base.Log;
 import org.chromium.base.VisibleForTesting;
 import org.chromium.chrome.browser.ChromeBackgroundServiceWaiter;
 import org.chromium.chrome.browser.offlinepages.interfaces.BackgroundSchedulerProcessor;
 
 /**
  * Handles servicing of background offlining requests coming via the GcmNetworkManager.
  */
 public class BackgroundOfflinerTask {
     private static final String TAG = "BGOfflinerTask";
+    private static final long DEFER_START_SECONDS = 5 * 60;
 
     public BackgroundOfflinerTask(BackgroundSchedulerProcessor bridge) {
         mBridge = bridge;
     }
 
     private final BackgroundSchedulerProcessor mBridge;
 
     /**
      * Triggers processing of background offlining requests.  This is called when
      * system conditions are appropriate for background offlining, typically from the
      * GcmTaskService onRunTask() method.  In response, we will start the
      * task processing by passing the call along to the C++ RequestCoordinator.
      * Also starts UMA collection.
      *
      * @returns true for success
      */
     public boolean startBackgroundRequests(Context context, Bundle bundle,
                                            ChromeBackgroundServiceWaiter waiter) {
+        // Set up backup scheduled task in case processing is killed before RequestCoordinator
+        // has a chance to reschedule base on remaining work.
+        BackgroundScheduler.schedule(context, DEFER_START_SECONDS);
+
+        // Now initiate processing.
         processBackgroundRequests(bundle, OfflinePageUtils.getDeviceConditions(context), waiter);
 
         // Gather UMA data to measure how often the user's machine is amenable to background
         // loading when we wake to do a task.
         long taskScheduledTimeMillis = TaskExtrasPacker.unpackTimeFromBundle(bundle);
         OfflinePageUtils.recordWakeupUMA(context, taskScheduledTimeMillis);
 
         return true;
     }
 
@@ skipping 24 matching lines @@
                 // Release the wake lock.
                 Log.d(TAG, "onProcessingDone");
                 waiter.onWaitDone();
             }
         };
 
         // Pass the activation on to the bridge to the C++ RequestCoordinator.
         mBridge.startProcessing(deviceConditions, callback);
     }
 }