Ensure jobs have a Context during onAdded().

Fixes a crash.

src/org/thoughtcrime/securesms/ApplicationContext.java

@@ -171,7 +171,7 @@ public class ApplicationContext extends MultiDexApplication implements Dependenc
                                                   .setMinimumLoggingLevel(android.util.Log.DEBUG)
                                                   .build());
 
-    this.jobManager = new JobManager(WorkManager.getInstance());
+    this.jobManager = new JobManager(this, WorkManager.getInstance());
   }
 
   public void initializeMessageRetrieval() {

src/org/thoughtcrime/securesms/jobmanager/Job.java

@@ -107,8 +107,13 @@ public abstract class Job extends Worker implements Serializable {
     }
   }
 
-  final void onSubmit(UUID id) {
+  final void onSubmit(@NonNull Context context, @NonNull UUID id) {
     Log.i(TAG, buildLog(id, "onSubmit()"));
+
+    if (this instanceof ContextDependent) {
+      ((ContextDependent) this).setContext(context);
+    }
+
     onAdded();
   }
 

src/org/thoughtcrime/securesms/jobmanager/JobManager.java

@@ -1,5 +1,6 @@
 package org.thoughtcrime.securesms.jobmanager;
 
+import android.content.Context;
 import android.support.annotation.NonNull;
 
 import java.util.concurrent.Executor;
@@ -22,10 +23,12 @@ public class JobManager {
 
   private final Executor executor = Executors.newSingleThreadExecutor();
 
+  private final Context     context;
   private final WorkManager workManager;
 
-  public JobManager(@NonNull WorkManager workManager) {
+  public JobManager(@NonNull Context context, @NonNull WorkManager workManager) {
-    this.workManager  = workManager;
+    this.context     = context;
+    this.workManager = workManager;
   }
 
   public void add(Job job) {
@@ -56,7 +59,7 @@ public class JobManager {
 
       OneTimeWorkRequest request = requestBuilder.build();
 
-      job.onSubmit(request.getId());
+      job.onSubmit(context, request.getId());
 
       String groupId = jobParameters.getGroupId();
       if (groupId != null) {