Parse a file for history records yielding dicts.

    Yields:
      Dicts containing browser history

def _DoParse(self):
    """Parse a file for history records yielding dicts.

    Yields:
      Dicts containing browser history
    """
    get4 = lambda x: struct.unpack("<L", self.input_dat[x:x + 4])[0]
    filesize = get4(0x1c)
    offset = get4(0x20)
    coffset = offset
    while coffset < filesize:
      etype = struct.unpack("4s", self.input_dat[coffset:coffset + 4])[0]
      if etype == b"REDR":
        pass
      elif etype in [b"URL "]:
        # Found a valid record
        reclen = get4(coffset + 4) * self.BLOCK_SIZE
        yield self._GetRecord(coffset, reclen)
      coffset += self.BLOCK_SIZE