Add `Attachment.isVisualMedia`

ts/types/Attachment.ts

@@ -1,3 +1,6 @@
+import is from '@sindresorhus/is';
+
+import * as GoogleChrome from '../GoogleChrome';
 import { MIMEType } from './MIME';
 
 
@@ -16,4 +19,16 @@ export interface Attachment {
   // key?: ArrayBuffer;
   // digest?: ArrayBuffer;
   // flags?: number;
-}
+};
+
+export const isVisualMedia = (attachment: Attachment): boolean => {
+  const { contentType } = attachment;
+
+  if (is.undefined(contentType)) {
+    return false;
+  }
+
+  const isSupportedImageType = GoogleChrome.isImageTypeSupported(contentType);
+  const isSupportedVideoType = GoogleChrome.isVideoTypeSupported(contentType);
+  return isSupportedImageType || isSupportedVideoType;
+};