Add an empty Android implementation of the PhysicalWebDataSource

chrome/browser/android/physical_web/physical_web_data_source_android.h

+// 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.
+
+#ifndef CHROME_BROWSER_ANDROID_PHYSICAL_WEB_PHYSICAL_WEB_DATA_SOURCE_ANDROID_H_
+#define CHROME_BROWSER_ANDROID_PHYSICAL_WEB_PHYSICAL_WEB_DATA_SOURCE_ANDROID_H_
+
+#include "base/macros.h"
+#include "components/physical_web/data_source/physical_web_data_source.h"
+
+namespace base {
+class ListValue;
+}
+
+class PhysicalWebDataSourceAndroid : public PhysicalWebDataSource {
+ public:
+  PhysicalWebDataSourceAndroid();
+  ~PhysicalWebDataSourceAndroid() override;
+
+  void StartDiscovery(bool network_request_enabled) override;
+  void StopDiscovery() override;
+
+  std::unique_ptr<base::ListValue> GetMetadata() override;
+  bool HasUnresolvedDiscoveries() override;
+
+  void RegisterListener(PhysicalWebListener* listener) override;
+  void UnregisterListener(PhysicalWebListener* listener) override;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(PhysicalWebDataSourceAndroid);
+};
+
+#endif  // CHROME_BROWSER_ANDROID_PHYSICAL_WEB_PHYSICAL_WEB_DATA_SOURCE_ANDROID_H_