Propagate full Error object to unprivileged MediaApp upon SaveCopy error.

Previously when we encountered an error during SaveCopy, we would sometimes just pass the error name and miss out on a lot of useful information. This CL removes that handling and just lets the error object propagate through the app.

Other half of this change is http://cl/317591265.

Bug: b/152809763
Change-Id: I65017f6b5359a8f22a7e9a33952b980f547833d2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2256115Reviewed-by: Bugs Nash <bugsnash@chromium.org>
Commit-Queue: Mitchell McDermott <mcdermottm@google.com>
Cr-Commit-Position: refs/heads/master@{#781195}

chromeos/components/media_app_ui/resources/js/launch.js

@@ -150,24 +150,11 @@ guestMessagePipe.registerHandler(Message.SAVE_COPY, async (message) => {
     // provide an extension automatically. See crbug/1082624#c23.
     excludeAcceptAllOption: true,
   };
+  // This may throw an error, but we can handle and recover from it on the
+  // unprivileged side.
   /** @type {!FileSystemHandle} */
-  let fileSystemHandle;
-  // chooseFileSystem is where recoverable errors happen, errors in the write
-  // process should be treated as unexpected and propagated through
-  // MessagePipe's standard exception handling.
-  try {
-    fileSystemHandle =
-        /** @type {!FileSystemHandle} */ (
-            await window.chooseFileSystemEntries(options));
-  } catch (/** @type {!DOMException} */ err) {
-    if (err.name !== 'SecurityError' && err.name !== 'AbortError') {
-      // Unknown error.
-      throw err;
-    }
-    console.log(`Aborting SAVE_COPY: ${err.message}`);
-    return err.name;
-  }
-
+  const fileSystemHandle = /** @type {!FileSystemHandle} */ (
+      await window.chooseFileSystemEntries(options));
   const {handle} = await getFileFromHandle(fileSystemHandle);
   // Note `handle` could be the same as a `FileSystemFileHandle` that exists in
   // `tokenMap`. Possibly even the `File` currently open. But that's OK. E.g.

chromeos/components/media_app_ui/resources/js/media_app.externs.js

@@ -129,9 +129,7 @@ mediaApp.ClientApiDelegate.prototype.openFeedbackDialog = function() {};
  * Saves a copy of `file` in a custom location with a custom
  * name which the user is prompted for via a native save file dialog.
  * @param {!mediaApp.AbstractFile} file
- * @return {!Promise<?string>} Promise which resolves when the request has been
- *     acknowledged. If the dialog could not be opened the promise resolves with
- *     an error message. Otherwise, with null after writing is complete.
+ * @return {!Promise<undefined>}
  */
 mediaApp.ClientApiDelegate.prototype.saveCopy = function(file) {};
 

chromeos/components/media_app_ui/resources/js/receiver.js

@@ -150,15 +150,12 @@ const DELEGATE = {
   },
   /**
    * @param {!mediaApp.AbstractFile} abstractFile
-   * @return {!Promise<?string>}
+   * @return {!Promise<undefined>}
    */
-  async saveCopy(abstractFile) {
+  async saveCopy(/** !mediaApp.AbstractFile */ abstractFile) {
     /** @type {!SaveCopyMessage} */
     const msg = {blob: abstractFile.blob, suggestedName: abstractFile.name};
-    const response =
-        /** @type {!SaveCopyResponse} */ (
-            await parentMessagePipe.sendMessage(Message.SAVE_COPY, msg));
-    return response.errorMessage;
+    await parentMessagePipe.sendMessage(Message.SAVE_COPY, msg);
   }
 };