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..0ff6e3edb64e05b83e93cb021c959f794ebec4c8
--- /dev/null
+++ b/components/physical_web/eddystone/eddystone_encoder.h
@@ -0,0 +1,27 @@
+// 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 {
+/*
+ * EncodeUrl takes a URL in the form of a std::string and

[mattreynolds, 2017/03/09 22:11:31]

Would it make sense to take a GURL as the input param?

[iankc, 2017/03/09 23:17:50]

Acknowledged.

+ * a pointer to a uint8_t vector to populate with the eddystone
+ * encoding of the url.
+ * Returns:
+ *   -1 If the Url parameter is empty.
+ *   -2 If the Url parameter is not a valid Url.
+ *   -3 If the Url parameter is not a standard Https or Http Url.
+ *   Length of encoded Url.
+ * Eddystone spec can be found here:
+ * https://github.com/google/eddystone/blob/master/protocol-specification.md

[mattreynolds, 2017/03/09 22:11:31]

Nice comment! A few things to clean up:

* Use all-caps for initialisms like URL and HTTP
* Capitalize Eddystone
* Use the error code names once you've added them

[iankc, 2017/03/09 23:17:50]

Done.

+ */
+int EncodeUrl(const std::string& url, std::vector<uint8_t>* encoded_url);
+}
+
+#endif  // COMPONENTS_PHYSICAL_WEB_EDDYSTONE_EDDYSTONE_ENCODER_H_