Merge \"Fix google-explicit-constructor warnings in system/core.\"

class BacktraceMock : public Backtrace {

 public:

  BacktraceMock(BacktraceMapMock* map) : Backtrace(0, 0, map) {

  explicit BacktraceMock(BacktraceMapMock* map) : Backtrace(0, 0, map) {

    if (map_ == nullptr) {

      abort();

    }

  protected:

    // Protected constructor to force factory function use.

    Socket(cutils_socket_t sock);

    explicit Socket(cutils_socket_t sock);

    // Blocks up to |timeout_ms| until a read is possible on |sock_|, and sets |receive_timed_out_|

    // as appropriate to help distinguish between normal timeouts and fatal errors. Returns true if

class Action {

public:

    Action(bool oneshot = false);

    explicit Action(bool oneshot = false);

    bool AddCommand(const std::vector<std::string>& args,

                    const std::string& filename, int line, std::string* err);

// a TOK_NEWLINE will not be generated for that line.

class Tokenizer {

 public:

  Tokenizer(const std::string& data);

  explicit Tokenizer(const std::string& data);

  ~Tokenizer();

  enum TokenType { TOK_START, TOK_END, TOK_NEWLINE, TOK_TEXT };

class UnwindMap : public BacktraceMap {

public:

  UnwindMap(pid_t pid);

  explicit UnwindMap(pid_t pid);

  unw_map_cursor_t* GetMapCursor() { return &map_cursor_; }

class UnwindMapRemote : public UnwindMap {

public:

  UnwindMapRemote(pid_t pid);

  explicit UnwindMapRemote(pid_t pid);

  virtual ~UnwindMapRemote();

  bool Build() override;