Remove duplicate CPU detection code; use base::CPU instead.

media/base/cpu_features.h

-// 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.
-
-// This file provide utility functions to check CPU features such as SSE2,
-// NEON.
-
-#ifndef MEDIA_BASE_CPU_FEATURES_H_
-#define MEDIA_BASE_CPU_FEATURES_H_
-
-namespace media {
-
-// Returns true if CPU has MMX support.
-bool hasMMX();
-
-// Returns true if CPU has SSE support.
-bool hasSSE();
-
-// Returns true if CPU has SSE2 support.
-bool hasSSE2();
-
-// Returns true if CPU supports SSE2, SSE3, and SSSE3.
-bool hasSSSE3();
-
-}  // namespace media
-
-#endif  // MEDIA_BASE_CPU_FEATURES_H_