Add palette dependency to Android.mk.

Change-Id: I34fcfa87a35df8ec1029669d6b570c1a95029b66
diff --git a/Android.mk b/Android.mk
index 0773869..e42a463 100644
--- a/Android.mk
+++ b/Android.mk
@@ -26,7 +26,8 @@
 LOCAL_STATIC_JAVA_LIBRARIES := \
     libWallpaperPicker \
     android-support-v4 \
-    android-support-v7-recyclerview
+    android-support-v7-recyclerview \
+    android-support-v7-palette
 
 LOCAL_SRC_FILES := $(call all-java-files-under, src) \
     $(call all-proto-files-under, protos)