media: Add unittest for MojoRenderer{Impl|Service}

media/base/mock_filters.h

 // Copyright (c) 2012 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 MEDIA_BASE_MOCK_FILTERS_H_
 #define MEDIA_BASE_MOCK_FILTERS_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 334 matching lines @@
 };
 
 class MockCdmContext : public CdmContext {
  public:
   MockCdmContext();
   ~MockCdmContext() override;
 
   MOCK_METHOD0(GetDecryptor, Decryptor*());
   int GetCdmId() const override;
 
+  void set_cdm_id(int cdm_id);
+
  private:
+  int cdm_id_ = CdmContext::kInvalidCdmId;
+
   DISALLOW_COPY_AND_ASSIGN(MockCdmContext);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_MOCK_FILTERS_H_