code: function _validateFrame(entry) {
          var deferred = new $.Deferred(),
              fileEntry = FileSystem.getFileForPath(entry.filePath);
  
          if (entry.inMem) {
              var indexInWS = MainViewManager.findInWorkingSet(entry.paneId, entry.filePath);
              // Remove entry if InMemoryFile is not found in Working set
              if (indexInWS === -1) {
                  deferred.reject();
              } else {
                  deferred.resolve();
              }
          } else {
              fileEntry.exists(function (err, exists) {
                  if (!err && exists) {
                      // Additional check to handle external modification and mutation of the doc text affecting markers
                      if (fileEntry._hash !== entry._hash) {
                          deferred.reject();
                      } else if (!entry._validateMarkers()) {
                          deferred.reject();
                      } else {
                          deferred.resolve();
                      }
                  } else {
                      deferred.reject();
                  }
              });
          }
  
          return deferred.promise();
      }
docs: Function to check existence of a file entry, validity of markers
  @private