Remove media::VideoDecodeContext as it has no implementation and is unused.

media/video/video_mock_objects.cc

Index: media/video/video_mock_objects.cc
diff --git a/media/video/video_mock_objects.cc b/media/video/video_mock_objects.cc
deleted file mode 100644
index e89fb650afb3bec4e4e6183c2fa8e37e1906471c..0000000000000000000000000000000000000000
--- a/media/video/video_mock_objects.cc
+++ /dev/null
@@ -1,18 +0,0 @@
-// Copyright (c) 2011 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.
-
-#include "media/video/video_mock_objects.h"
-
-namespace media {
-
-MockVideoDecodeEngine::MockVideoDecodeEngine() {}
-
-MockVideoDecodeEngine::~MockVideoDecodeEngine() {}
-
-MockVideoDecodeContext::MockVideoDecodeContext() {}
-
-MockVideoDecodeContext::~MockVideoDecodeContext() {}
-
-
-}  // namespace media