Phonehub: fix notification timestamp

Was previously calculating notification timestamp from a Unix epoch
time source. This patch fixes this by properly converting the timestamp
to Windows FILETIME epoch.

Bug: 1106937
Fixed: 1141587
Change-Id: I6d085a2b6449f8a8424a8c3e203939659d8bb32c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2493429
Commit-Queue: Jimmy Gong <jimmyxgong@chromium.org>
Reviewed-by: Kyle Horimoto <khorimoto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#820521}

chromeos/components/phonehub/phone_status_processor.cc

@@ -141,8 +141,7 @@ base::Optional<Notification> ProcessNotificationProto(
           base::UTF8ToUTF16(proto.origin_app().visible_name()),
           proto.origin_app().package_name(),
           CreateImageFromSerializedIcon(proto.origin_app().icon())),
-      base::Time::FromDeltaSinceWindowsEpoch(
-          base::TimeDelta::FromMilliseconds(proto.epoch_time_millis())),
+      base::Time::FromJsTime(proto.epoch_time_millis()),
       GetNotificationImportanceFromProto(proto.importance()), actions_it->id(),
       title, text_content, shared_image, contact_image);
 }