[Android] Reimplementing BTSJobSerivce delegate to not overwrite tasks

components/background_task_scheduler/android/java/src/org/chromium/components/background_task_scheduler/BackgroundTaskSchedulerJobService.java

Index: components/background_task_scheduler/android/java/src/org/chromium/components/background_task_scheduler/BackgroundTaskSchedulerJobService.java
diff --git a/components/background_task_scheduler/android/java/src/org/chromium/components/background_task_scheduler/BackgroundTaskSchedulerJobService.java b/components/background_task_scheduler/android/java/src/org/chromium/components/background_task_scheduler/BackgroundTaskSchedulerJobService.java
index cf86dda2bc0c4cb72d8e0c89dc4cbd902943057e..4a19907d6a7fcb3c93f0fc3a3009998c2f7fca51 100644
--- a/components/background_task_scheduler/android/java/src/org/chromium/components/background_task_scheduler/BackgroundTaskSchedulerJobService.java
+++ b/components/background_task_scheduler/android/java/src/org/chromium/components/background_task_scheduler/BackgroundTaskSchedulerJobService.java
@@ -18,6 +18,7 @@ import org.chromium.base.Log;
 import org.chromium.base.ThreadUtils;
 import org.chromium.base.VisibleForTesting;
 
+import java.util.List;
 /**
  * An implementation of {@link BackgroundTaskSchedulerDelegate} that uses the system
  * {@link JobScheduler} to schedule jobs.
@@ -141,8 +142,8 @@ class BackgroundTaskSchedulerJobService implements BackgroundTaskSchedulerDelega
         JobScheduler jobScheduler =
                 (JobScheduler) context.getSystemService(Context.JOB_SCHEDULER_SERVICE);
 
-        if (taskInfo.shouldUpdateCurrent()) {
-            jobScheduler.cancel(taskInfo.getTaskId());
+        if (!taskInfo.shouldUpdateCurrent() && hasPendingJob(jobScheduler, taskInfo.getTaskId())) {
+            return true;
         }
 
         int result = jobScheduler.schedule(jobInfo);
@@ -156,4 +157,13 @@ class BackgroundTaskSchedulerJobService implements BackgroundTaskSchedulerDelega
                 (JobScheduler) context.getSystemService(Context.JOB_SCHEDULER_SERVICE);
         jobScheduler.cancel(taskId);
     }
+
+    private boolean hasPendingJob(JobScheduler jobScheduler, int jobId) {
+        List<JobInfo> pendingJobs = jobScheduler.getAllPendingJobs();
+        for (JobInfo pendingJob : pendingJobs) {
+            if (pendingJob.getId() == jobId) return true;
+        }
+
+        return false;
+    }
 }