Add Platform Independent Eddystone Encoder

components/physical_web/eddystone/eddystone_encoder.h

+// 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;

[mattreynolds, 2017/03/09 23:39:48]

In C++, use "Url" when including an initialism in a CamelCase name. E.g.
HttpUrlRequest instead of HTTPURLRequest. (Chrome isn't very consistent on this
since the style decision was made recently, but new code should abide by the new
style.)

More info in this thread:
https://groups.google.com/a/chromium.org/d/msg/chromium-dev/k8-ztIrWaUY/UIOe3...

[iankc, 2017/03/10 22:28:45]

Done.

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