Add Platform Independent Eddystone Encoder

components/physical_web/eddystone/eddystone_encoder.h

Index: components/physical_web/eddystone/eddystone_encoder.h
diff --git a/components/physical_web/eddystone/eddystone_encoder.h b/components/physical_web/eddystone/eddystone_encoder.h
new file mode 100644
index 0000000000000000000000000000000000000000..72ba9fab63c981371a81f46834cab47a4520eb83
--- /dev/null
+++ b/components/physical_web/eddystone/eddystone_encoder.h
@@ -0,0 +1,34 @@
+// Copyright 2017 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_EDDYSTONE_EDDYSTONE_ENCODER_H_
+#define COMPONENTS_PHYSICAL_WEB_EDDYSTONE_EDDYSTONE_ENCODER_H_
+
+#include <string>
+#include <vector>
+
+namespace physical_web {
+
+const int kEmptyUrl = -1;
+const int kInvalidUrl = -2;
+const int kInvalidFormat = -3;
+const int kNullEncodedUrl = -4;
+
+/*
+ * EncodeUrl takes a URL in the form of a std::string and
+ * a pointer to a uint8_t vector to populate with the eddystone
+ * encoding of the URL.
+ * Returns:
+ *   kEmptyUrl If the URL parameter is empty.
+ *   kInvalidUrl If the URL parameter is not a valid Url.

[Olivier, 2017/03/13 11:57:56]

s/Url/URL for consistency

[iankc, 2017/03/13 17:53:01]

Done.

+ *   kInvalidFormat If the URL parameter is not a standard HTTPS or HTTP URL.

[Olivier, 2017/03/13 11:57:55]

or is IP URL.

[iankc, 2017/03/13 17:53:01]

Acknowledged.

+ *   kNullEncodedUrl If the encoded_url vector is NULL.
+ *   Length of encoded URL.
+ * Eddystone spec can be found here:
+ * https://github.com/google/eddystone/blob/master/protocol-specification.md
+ */
+int EncodeUrl(const std::string& url, std::vector<uint8_t>* encoded_url);
+}
+
+#endif  // COMPONENTS_PHYSICAL_WEB_EDDYSTONE_EDDYSTONE_ENCODER_H_