Moves thumbnail disabling logic into core.js

src/core/Core.js

@@ -395,8 +395,14 @@ class Uppy {
    */
   generatePreview (file) {
     if (Utils.isPreviewSupported(file.type) && !file.isRemote) {
-      Utils.createThumbnail(file, 200, this.opts.thumbnailGeneration).then((thumbnail) => {
-        this.setPreviewURL(file.id, thumbnail)
+      let previewPromise
+      if (this.opts.thumbnailGeneration === true) {
+        previewPromise = Utils.createThumbnail(file, 200)
+      } else {
+        previewPromise = Promise.resolve(URL.createObjectURL(file.data))
+      }
+      previewPromise.then((preview) => {
+        this.setPreviewURL(file.id, preview)
       }).catch((err) => {
         console.warn(err.stack || err.message)
       })

src/core/Utils.js

@@ -215,12 +215,8 @@ function getProportionalHeight (img, width) {
  * @param {number} width
  * @return {Promise}
  */
-function createThumbnail (file, targetWidth, shouldGenerateThumbnail) {
+function createThumbnail (file, targetWidth) {
   const originalUrl = URL.createObjectURL(file.data)
-  if (shouldGenerateThumbnail === false) {
-    return Promise.resolve(originalUrl)
-  }
-
   const onload = new Promise((resolve, reject) => {
     const image = new Image()
     image.src = originalUrl

src/core/Utils.test.js

@@ -275,18 +275,6 @@ describe('core/utils', () => {
       'should create a thumbnail of the specified image at the specified width',
       () => {}
     )
-    it(
-      'should bypass the creation of a thumbnail when the generateThumbnail param is false',
-      () => {
-        const file = {
-          data: 'foobar'
-        }
-        const targetWidth = 200
-        return utils.createThumbnail(file, targetWidth, false).then((url) => {
-          expect(url).toEqual('newUrl')
-        })
-      }
-    )
   })
 
   describe('dataURItoBlob', () => {