GN: Fix test_support_unittests and MIPS compile issue.

webrtc/system_wrappers/include/logcat_trace_context.h

 /*
  *  Copyright (c) 2013 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.
  */
 
 #ifndef WEBRTC_SYSTEM_WRAPPERS_INCLUDE_LOGCAT_TRACE_CONTEXT_H_
 #define WEBRTC_SYSTEM_WRAPPERS_INCLUDE_LOGCAT_TRACE_CONTEXT_H_
 
 #include "webrtc/system_wrappers/include/trace.h"
 
 #ifndef ANDROID
 #error This file only makes sense to include on Android!
 #endif
 
 namespace webrtc {
 
 // Scoped helper class for directing Traces to Android's logcat facility.  While
 // this object lives, Trace output will be sent to logcat.
 class LogcatTraceContext : public webrtc::TraceCallback {
  public:
   LogcatTraceContext();
-  virtual ~LogcatTraceContext();
+  ~LogcatTraceContext() override;
 
   // TraceCallback impl.
-  virtual void Print(TraceLevel level, const char* message, int length);
+  void Print(TraceLevel level, const char* message, int length) override;
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_SYSTEM_WRAPPERS_INCLUDE_LOGCAT_TRACE_CONTEXT_H_