Callback webrtc underlying logs to the application layer

1. Create subclass inheritance ::rtc::LogSink The underlying log class

enum LoggingSeverity {
  LS_VERBOSE,
  LS_INFO,
  LS_WARNING,
  LS_ERROR,
  LS_NONE,
};

class RtcFileLog : public ::rtc::LogSink {
    int SetLogFile(const char* filePath);
    int SetLogFileSize(unsigned int size);
}

//  Not android
void RtcFileLog::OnLogMessage(const std::string& msg, 
::rtc::LoggingSeverity severity) {
    ... Writing documents 
}
    
// android
void RtcFileLog::OnLogMessage(const std::string& msg, 
    ::rtc::LoggingSeverity severity, const char* tag) {
   ... Writing documents 
}

2. establish ::rtc::LogSink Log subclass , Set the callback class to rtc The bottom layer reports logs

std::unique_ptr<RtcFileLog> m_rtcFileLog;
if (!m_rtcFileLog){
    m_rtcFileLog.reset(new RtcFileLog());
}
// Initialize the log module 
rtc::LogMessage::LogToDebug(::rtc::LS_INFO);
rtc::LogMessage::LogTimestamps(true);
rtc::LogMessage::LogThreads(true);
// Set write file path 
m_rtcFileLog->SetLogFile(log_path.c_str());
// Add implementation class 
rtc::LogMessage::RemoveLogToStream(m_rtcFileLog.get());
rtc::LogMessage::AddLogToStream(m_rtcFileLog.get(), ::rtc::LS_INFO);