[Photo Editor] Make exif encoder more tolerant to non-standard EXIF data

chrome/browser/resources/file_manager/js/image_editor/exif_encoder.js

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // TODO:(kaznacheev) Share the EXIF constants with exif_parser.js
 var EXIF_MARK_SOS = 0xffda;  // Start of "stream" (the actual image data).
 var EXIF_MARK_SOI = 0xffd8;  // Start of image data.
 var EXIF_MARK_EOI = 0xffd9;  // End of image data.
 
 var EXIF_MARK_APP0 = 0xffe0;  // APP0 block, most commonly JFIF data.
@@ skipping 303 matching lines @@
   }
 
   // Write out the long values and resolve pointers.
   for (var i = 0; i != longValues.length; i++) {
     var longValue = longValues[i];
     bw.resolveOffset(longValue.id);
     ExifEncoder.writeValue(bw, longValue);
   }
 };
 
-// TODO(kaznacheev): Share with ExifParser?
-// TODO(JSDOC)
+/**
+ * @param {{format:number, id:number}} tag EXIF tag object.
+ * @return {number} Width in bytes of the data unit associated with this tag.
+ * TODO(kaznacheev): Share with ExifParser?
+ */
 ExifEncoder.getComponentWidth = function(tag) {
   switch (tag.format) {
     case 1:  // Byte
     case 2:  // String
     case 7:  // Undefined
       return 1;
 
     case 3:  // Short
       return 2;
 
     case 4:  // Long
     case 9:  // Signed Long
       return 4;
 
     case 5:  // Rational
     case 10:  // Signed Rational
       return 8;
 
     default:  // ???
-      throw new Error('Unknown tag format 0x' +
+      console.warn('Unknown tag format 0x' +
           Number(tag.id).toString(16) + ': ' + tag.format);
       return 4;
   }
 };
 
 /**
  * Writes out the tag value.
  * @param {ByteWriter} bw Writer to use.
  * @param {Object} tag Tag, which value to write.
  */
@@ skipping 20 matching lines @@
     if (tag.componentCount == 1) {
        writeComponent(tag.value, signed);
     } else {
       for (var i = 0; i != tag.componentCount; i++) {
         writeComponent(tag.value[i], signed);
       }
     }
   }
 };
 
-//TODO(JSDOC)
+/**
+ * @param {{Object.<number,Object>}} directory EXIF directory.
+ * @param {number} id Tag id.
+ * @param {number} format Tag format
+ *                        (used in {@link ExifEncoder#getComponentWidth}).
+ * @param {number} componentCount Number of components in this tag.
+ * @return {{id:number, format:number, componentCount:number}}
+ *     Tag found or created.
+ */
 ExifEncoder.findOrCreateTag = function(directory, id, format, componentCount) {
   if (!(id in directory)) {
     directory[id] = {
       id: id,
       format: format || 3,  // Short
       componentCount: componentCount || 1
     };
   }
   return directory[id];
 };
@@ skipping 150 matching lines @@
 };
 
 /**
  * Check if every forward has been resolved, throw and error if not.
  */
 ByteWriter.prototype.checkResolved = function() {
   for (var key in this.forwards_) {
     throw new Error('Unresolved forward pointer ' + key.toString(16));
   }
 };