[Android] BackgroundTaskScheduler reschedule implementation

components/background_task_scheduler/android/junit/src/org/chromium/components/background_task_scheduler/TestBackgroundTask.java

 // 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.components.background_task_scheduler;
 
 import android.content.Context;
 
 /** Dummy implementation of a background task used for testing. */
 class TestBackgroundTask implements BackgroundTask {
+    private static int sRescheduleCalls = 0;
+
     public TestBackgroundTask() {}
 
     @Override
     public boolean onStartTask(
             Context context, TaskParameters taskParameters, TaskFinishedCallback callback) {
         return false;
     }
 
     @Override
     public boolean onStopTask(Context context, TaskParameters taskParameters) {
         return false;
     }
+
+    @Override
+    public void reschedule(Context context) {
+        sRescheduleCalls++;
+    }
+
+    public static int getRescheduleCalls() {
+        return sRescheduleCalls;
+    }
+
+    public static void reset() {
+        sRescheduleCalls = 0;
+    }
 }