Update paint filer when updating thumbnail

Test: Enable task snapshots, go to recents, scroll, make sure no
jump in darkness of thumbnail

Change-Id: I5448192bd87259eb8a4e1e7b7c55c1aa82693d2e

packages/SystemUI/src/com/android/systemui/recents/views/TaskViewThumbnail.java

@@ -197,6 +197,7 @@ public class TaskViewThumbnail extends View {
                     bm.getHeight() - thumbnailData.insets.top - thumbnailData.insets.bottom);
             mThumbnailData = thumbnailData;
             updateThumbnailMatrix();
+            updateThumbnailPaintFilter();
         } else {
             mBitmapShader = null;
             mDrawPaint.setShader(null);