sysui: refactor for extension.

Make addTile in QSPanel return a TileRecord.

Bug: 28532600
Change-Id: I007d2f9caba410a8c9108e773822a467745b951c
(cherry picked from commit 63a18b4082f0ad9f8696f6a8a370a9df6210eebc)
diff --git a/packages/SystemUI/src/com/android/systemui/qs/QSPanel.java b/packages/SystemUI/src/com/android/systemui/qs/QSPanel.java
index 0786496..630f988 100644
--- a/packages/SystemUI/src/com/android/systemui/qs/QSPanel.java
+++ b/packages/SystemUI/src/com/android/systemui/qs/QSPanel.java
@@ -299,7 +299,7 @@
         return new QSTileView(mContext, tile.createTileView(mContext), collapsedView);
     }
 
-    protected void addTile(final QSTile<?> tile, boolean collapsedView) {
+    protected TileRecord addTile(final QSTile<?> tile, boolean collapsedView) {
         final TileRecord r = new TileRecord();
         r.tile = tile;
         r.tileView = createTileView(tile, collapsedView);
@@ -358,6 +358,8 @@
         if (mTileLayout != null) {
             mTileLayout.addTile(r);
         }
+
+        return r;
     }