Convert RapporRecorder to use mojo.

chrome/common/rappor_recorder.mojom

+// 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.
+
+module mojom;
+
+import "url/mojo/url.mojom";
+
+interface RapporRecorder {
+  // Records a sample string to a Rappor privacy-preserving metric.
+  // See: https://www.chromium.org/developers/design-documents/rappor
+  RecordRappor(string metric, string sample);
+
+  // Records a domain and registry of a url to a Rappor privacy-preserving
+  // metric. See: https://www.chromium.org/developers/design-documents/rappor
+  RecordRapporURL(string metric, url.mojom.Url url);
+};