MediaRouter: Pick dominant color for portrait art work's background

Change-Id: I718c518c0eb7f576b474a814c48483c03b1715a9
diff --git a/v7/mediarouter/src/android/support/v7/app/MediaRouteControllerDialog.java b/v7/mediarouter/src/android/support/v7/app/MediaRouteControllerDialog.java
index b18c9bb..1693e72 100644
--- a/v7/mediarouter/src/android/support/v7/app/MediaRouteControllerDialog.java
+++ b/v7/mediarouter/src/android/support/v7/app/MediaRouteControllerDialog.java
@@ -797,11 +797,11 @@
                     }
                 }
             }
-            if (art != null) {
-                if (art.getWidth() < art.getHeight()) {
-                    // Portrait art requires background color.
-                    mBackgroundColor = new Palette.Builder(art).generate().getDarkVibrantColor(0);
-                }
+            if (art != null && art.getWidth() < art.getHeight()) {
+                // Portrait art requires background color.
+                Palette palette = new Palette.Builder(art).maximumColorCount(1).generate();
+                mBackgroundColor = (palette.getSwatches() == null)
+                        ? 0 : palette.getSwatches().get(0).getRgb();
             }
             return art;
         }