Make in-progress download notification persistent on touchless

The only surface for interacting with downloads in touchless chrome is
through the notification system. This patch makes paused and
in-progress download notifications persistent so they can be accessed
even after notifications are cleared.

Bug: 989293
Change-Id: I8041e0bcb54996cccb7bdc1d37c2fdc15615bcfd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1737486Reviewed-by: David Trainor <dtrainor@chromium.org>
Reviewed-by: Shakti Sahu <shaktisahu@chromium.org>
Commit-Queue: Matthew Jones <mdjones@chromium.org>
Cr-Commit-Position: refs/heads/master@{#685367}

chrome/android/java/src/org/chromium/chrome/browser/download/DownloadNotificationFactory.java

@@ -222,6 +222,10 @@ public final class DownloadNotificationFactory {
                                         context, cancelIntent, downloadUpdate.getNotificationId()),
                                 cancelActionType);
 
+                // On touchless devices, the only access point for downloads is the notification, so
+                // keep the notification persistent if not in the completed or failure state.
+                if (FeatureUtilities.isNoTouchModeEnabled()) builder.setOngoing(true);
+
                 if (!downloadUpdate.getIsOffTheRecord())
                     builder.setLargeIcon(downloadUpdate.getIcon());