Add Platform Verification Mojo Services.

media/mojo/interfaces/platform_verification.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.
+
+// TODO(xhwang): Move this out of media if it is needed anywhere else.
+module media.interfaces;
+
+// Allows authorized services to verify that the underlying platform is trusted.
+// An example of a trusted platform is a Chrome OS device in verified boot mode.
+// This can be used for protected content playback.
+//
+// Input parameters:
+// - |service_id|: the service ID for the |challenge|.
+// - |challenge|: the challenge data.
+//
+// Output parameters:
+// - |success|: whether the platform is successfully verified. If true/false the
+//              following 3 parameters should be non-empty/empty.
+// - |signed_data|: the data signed by the platform.
+// - |signed_data_signature|: the signature of the signed data block.
+// - |platform_key_certificate|: the device specific certificate for the
+//                               requested service.
+interface PlatformVerification {
+  ChallengePlatform(string service_id, string challenge) =>
+      (bool success,
+       string? signed_data,
+       string? signed_data_signature,
+       string? platform_key_certificate);
+};