Fix issue #17674789: Recents icon resets if persist mode is 'persistNever'

Changed TaskPersister worker thread to not delete task information on disk
for tasks that are in recents but not persistable.

Also, changed logic that writes tasks information (excluding thunmbnail)
to disk to not write information for tasks that are not persistable.

Bug: 17674789
Change-Id: Iff7c5d24677f8a75157bb6be504fc2d9d6bcc098
diff --git a/services/core/java/com/android/server/am/TaskPersister.java b/services/core/java/com/android/server/am/TaskPersister.java
index afc781f..b331c84 100644
--- a/services/core/java/com/android/server/am/TaskPersister.java
+++ b/services/core/java/com/android/server/am/TaskPersister.java
@@ -166,7 +166,7 @@
                         break;
                     }
                 }
-                if (queueNdx < 0) {
+                if (queueNdx < 0 && task.isPersistable) {
                     mWriteQueue.add(new TaskWriteQueueItem(task));
                 }
             } else {
@@ -473,13 +473,15 @@
                         if (DEBUG) Slog.d(TAG, "mRecents=" + tasks);
                         for (int taskNdx = tasks.size() - 1; taskNdx >= 0; --taskNdx) {
                             final TaskRecord task = tasks.get(taskNdx);
-                            if (DEBUG) Slog.d(TAG, "LazyTaskWriter: task=" + task + " persistable=" +
-                                    task.isPersistable);
-                            if (task.isPersistable && !task.stack.isHomeStack()) {
+                            if (DEBUG) Slog.d(TAG, "LazyTaskWriter: task=" + task +
+                                    " persistable=" + task.isPersistable);
+                            if ((task.isPersistable || task.inRecents)
+                                    && !task.stack.isHomeStack()) {
                                 if (DEBUG) Slog.d(TAG, "adding to persistentTaskIds task=" + task);
                                 persistentTaskIds.add(task.taskId);
                             } else {
-                                if (DEBUG) Slog.d(TAG, "omitting from persistentTaskIds task=" + task);
+                                if (DEBUG) Slog.d(TAG,
+                                        "omitting from persistentTaskIds task=" + task);
                             }
                         }
                     }