media: Support creation and SetCdm() for mojo based CDM.

media/mojo/interfaces/content_decryption_module_factory.mojom

Index: media/mojo/interfaces/content_decryption_module_factory.mojom
diff --git a/media/mojo/interfaces/content_decryption_module_factory.mojom b/media/mojo/interfaces/content_decryption_module_factory.mojom
new file mode 100644
index 0000000000000000000000000000000000000000..8c84f6943c9a116843a234f19ba1379a0eabd857
--- /dev/null
+++ b/media/mojo/interfaces/content_decryption_module_factory.mojom
@@ -0,0 +1,15 @@
+// Copyright 2014 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 mojo;
+
+import "media/mojo/interfaces/content_decryption_module.mojom";
+
+// An interface to request a ContentDecryptionModule service.
+interface ContentDecryptionModuleFactory {
+  Create(string key_system,
+         string security_origin,
+         int32 cdm_id,
+         ContentDecryptionModule&? cdm);
+};