Expose Physical Web metadata to native clients over JNI

components/physical_web/data_source/physical_web_data_source.cc

Index: components/physical_web/data_source/physical_web_data_source.cc
diff --git a/components/physical_web/data_source/physical_web_data_source.cc b/components/physical_web/data_source/physical_web_data_source.cc
new file mode 100644
index 0000000000000000000000000000000000000000..31e8349694a27fa3d6c998c6593c3ca4c9d8e009
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+++ b/components/physical_web/data_source/physical_web_data_source.cc
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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.
+
+#include "components/physical_web/data_source/physical_web_data_source.h"
+
+const char kPhysicalWebDescriptionKey[] = "description";
+const char kPhysicalWebDistanceEstimateKey[] = "distanceEstimate";
+const char kPhysicalWebGroupIdKey[] = "groupId";
+const char kPhysicalWebIconUrlKey[] = "icon";
+const char kPhysicalWebResolvedUrlKey[] = "resolvedUrl";
+const char kPhysicalWebScanTimestampKey[] = "scanTimestamp";
+const char kPhysicalWebScannedUrlKey[] = "scannedUrl";
+const char kPhysicalWebTitleKey[] = "title";