Add download file API

Summary: Changelog: Expose "downloadFile" API to Flipper plugins. Allow them to download files form the web to Flipper Server.

Reviewed By: mweststrate

Differential Revision: D32950685

fbshipit-source-id: 7b7f666e165ff7bf209230cdc96078272ede3616

desktop/flipper-plugin/src/plugin/FlipperLib.tsx

@@ -18,6 +18,9 @@ import {
   ExecOut,
   BufferEncoding,
   MkdirOptions,
+  DownloadFileStartOptions,
+  DownloadFileStartResponse,
+  DownloadFileUpdate,
 } from 'flipper-common';
 
 export type FileEncoding = 'utf-8' | 'base64';
@@ -28,6 +31,13 @@ export interface FileDescriptor {
   path?: string;
 }
 
+export interface DownloadFileResponse extends DownloadFileStartResponse {
+  /**
+   * Indicates whether a download is completed. Resolves with the number of downloaded bytes. Rejects if the download has errors.
+   */
+  completed: Promise<number>;
+}
+
 export type RemoteServerContext = {
   childProcess: {
     exec(
@@ -49,6 +59,13 @@ export type RemoteServerContext = {
     ): Promise<void>;
     copyFile(src: string, dest: string, flags?: number): Promise<void>;
   };
+  downloadFile(
+    url: string,
+    dest: string,
+    options?: DownloadFileStartOptions & {
+      onProgressUpdate?: (progressUpdate: DownloadFileUpdate) => void;
+    },
+  ): Promise<DownloadFileResponse>;
 };
 
 /**