media: Add ProvisionFetcher mojo interface and implementation.

media/mojo/interfaces/provision_fetcher.mojom

+// Copyright 2015 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 media.interfaces;
+
+// An interface to retrieve provision information for Android MediaDrm.
+// See Android documentation about MediaDrm provisioning:
+// https://developer.android.com/reference/android/media/MediaDrm.ProvisionRequest.html
+
+interface ProvisionFetcher {
+  // Requests the provision information with |default_url| and |request_data|
+  // and returns |result| and the |response|. The input parameters |default_url|
+  // and |request_data| corresponds to Java class MediaDrm.ProvisionRequest.
+  // |response| will be null iff |result| is false.
+  Retrieve(string default_url, string request_data)
+      => (bool result, string? response);
+};