Add an empty Android implementation of the PhysicalWebDataSource

chrome/browser/android/physical_web/physical_web_data_source_android.cc

+// 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.
+
+#include "chrome/browser/android/physical_web/physical_web_data_source_android.h"
+
+#include "base/memory/ptr_util.h"
+#include "base/values.h"
+
+PhysicalWebDataSourceAndroid::PhysicalWebDataSourceAndroid() {
+}
+
+PhysicalWebDataSourceAndroid::~PhysicalWebDataSourceAndroid() {
+}
+
+void PhysicalWebDataSourceAndroid::StartDiscovery(
+    bool network_request_enabled) {
+}
+
+void PhysicalWebDataSourceAndroid::StopDiscovery() {
+}
+
+std::unique_ptr<base::ListValue> PhysicalWebDataSourceAndroid::GetMetadata() {
+  return base::MakeUnique<base::ListValue>();
+}
+
+bool PhysicalWebDataSourceAndroid::HasUnresolvedDiscoveries() {
+  return false;
+}
+
+void PhysicalWebDataSourceAndroid::RegisterListener(
+    PhysicalWebListener* listener) {
+}
+
+void PhysicalWebDataSourceAndroid::UnregisterListener(
+    PhysicalWebListener* listener) {
+}