Revert "Update includes for webrtc/{base => rtc_base} rename (3/3)"

webrtc/rtc_base/memory_usage_unittest.cc

 /*
  *  Copyright (c) 2017 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
-#include "webrtc/rtc_base/memory_usage.h"
+#include "webrtc/base/memory_usage.h"
 #include <cstdio>
 #include "webrtc/test/gtest.h"
 
 namespace rtc {
 
 TEST(GetMemoryUsage, SimpleTest) {
   int64_t used_bytes = GetProcessResidentSizeBytes();
   EXPECT_GE(used_bytes, 0);
 }
 
 }  // namespace rtc