Convert MediaLog from being ref counted to owned by WebMediaPlayer.

testing/libfuzzer/fuzzers/mp4_box_reader_fuzzer.cc

 // Copyright 2015 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 <stddef.h>
 #include <stdint.h>
 
 #include <memory>
 
+#include "base/logging.h"
 #include "media/formats/mp4/box_reader.h"
-#include "base/logging.h"
 
 class NullMediaLog : public media::MediaLog {
  public:
   NullMediaLog() {}
 
   void DoAddEventLogString(const std::string& event) {}
 
   void AddEvent(std::unique_ptr<media::MediaLogEvent> event) override {}
 
  protected:
   virtual ~NullMediaLog() {}
 
  private:
   DISALLOW_COPY_AND_ASSIGN(NullMediaLog);
 };
 
 // Entry point for LibFuzzer.
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
   bool err;
-  scoped_refptr<NullMediaLog> media_log(new NullMediaLog());
+  NullMediaLog media_log;
   std::unique_ptr<media::mp4::BoxReader> reader(
       media::mp4::BoxReader::ReadTopLevelBox(data, static_cast<const int>(size),
-                                             media_log, &err));
+                                             &media_log, &err));
   if (err) {
     return 0;
   }
   if (reader == NULL) {
     return 0;
   }
   if (!reader->ScanChildren()) {
     return 0;
   }
   return 0;
 }