Enable Popular Sites in Android demo mode.

components/ntp_tiles/android/BUILD.gn

+# Copyright 2016 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import("//build/config/android/rules.gni")
+
+_jni_sources =
+    [ "java/src/org/chromium/components/ntptiles/MostVisitedSites.java" ]
+
+# GYP: //components/ntp_tiles.gypi:ntp_tiles_jni_headers
+generate_jni("ntp_tiles_jni_headers") {
+  sources = _jni_sources
+  jni_package = "ntp_tiles"
+}
+
+# GYP: //components/ntp_tiles.gypi:ntp_tiles_java
+android_library("ntp_tiles_java") {
+  deps = [
+    "//base:base_java",
+  ]
+  java_files = [] + _jni_sources
+}