Add a Physical Web data source

components/physical_web_data_source/physical_web_data_source.h

Index: components/physical_web_data_source/physical_web_data_source.h
diff --git a/components/physical_web_data_source/physical_web_data_source.h b/components/physical_web_data_source/physical_web_data_source.h
new file mode 100644
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+++ b/components/physical_web_data_source/physical_web_data_source.h
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+// 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 COMPONENTS_PHYSICAL_WEB_DATA_SOURCE_PHYSICAL_WEB_DATA_SOURCE_H_
+#define COMPONENTS_PHYSICAL_WEB_DATA_SOURCE_PHYSICAL_WEB_DATA_SOURCE_H_
+
+#include <memory>
+
+#include "base/values.h"
+
+// Helper class for accessing Physical Web metadata and controlling the scanner.
+class PhysicalWebDataSource {
+ public:
+  PhysicalWebDataSource();
+  virtual ~PhysicalWebDataSource();
+
+  // Returns the global instance of the PhysicalWebDataSource singleton. This
+  // does not create the singleton and will return NULL if an instance has not
+  // yet been set with SetInstance.
+  static PhysicalWebDataSource* GetInstance();
+
+  // Sets the global instance of the PhysicalWebDataSource singleton.
+  static void SetInstance(PhysicalWebDataSource* instance);
+
+  // Starts scanning for Physical Web URLs. If |network_request_enabled| is
+  // true, discovered URLs will be sent to a resolution service.
+  virtual void StartDiscovery(bool network_request_enabled) = 0;
+
+  // Stops scanning for Physical Web URLs and clears cached URL content.
+  virtual void StopDiscovery() = 0;
+
+  // Returns a list of resolved URLs and associated page metadata. If network
+  // requests are disabled, the list will be empty.
+  virtual std::unique_ptr<base::ListValue> GetMetadata() = 0;
+
+  // Returns boolean |true| if network requests are disabled and there are one
+  // or more discovered URLs that have not been sent to the resolution service.
+  virtual bool HasUnresolvedDiscoveries() = 0;
+};
+
+#endif  // COMPONENTS_PHYSICAL_WEB_DATA_SOURCE_PHYSICAL_WEB_DATA_SOURCE_H_