packager: buck library: expose asset content

Reviewed By: davidaurelio

Differential Revision: D4945778

fbshipit-source-id: ea132a3d284ed09c59c69afbdd7b707af9e521b9

packager/src/ModuleGraph/types.flow.js

@@ -140,3 +140,11 @@ export type LibraryOptions = {|
   platform?: string,
   root: string,
 |};
+
+export type Base64Content = string;
+
+export type Library = {|
+  files: Array<TransformedFile>,
+  /* cannot be a Map because it's JSONified later on */
+  assets: {[destFilePath: string]: Base64Content},
+|};