1 files changed, 16 insertions, 0 deletions
diff --git a/chrome/browser/resources/file_manager/js/util.js b/chrome/browser/resources/file_manager/js/util.js
index bd3b08a..ec14e95 100644
--- a/chrome/browser/resources/file_manager/js/util.js
+++ b/chrome/browser/resources/file_manager/js/util.js
@@ -166,4 +166,20 @@ var util = {
     return fmt(this.scale_[i], this.units_[i]);
   },
 
+  /**
+   * Utility function to read specified range of bytes from file
+   * @param file {File} file to read
+   * @param begin {int} starting byte(included)
+   * @param end {int} last byte(excluded)
+   * @param callback {function(File, Uint8Array)} callback to invoke
+   * @param onError {function(err)} error handler
+   */
+  readFileBytes: function(file, begin, end, callback, onError) {
+    var fileReader = new FileReader();
+    fileReader.onerror = onError;
+    fileReader.onloadend = function() {
+      callback(file, new ByteReader(fileReader.result))
+    };
+    fileReader.readAsArrayBuffer(file.webkitSlice(begin, end));
+  }
 };