[Files app] VolumeManagerImpl.initialize() returns a Promise<void>

Change-Id: I739a6ed2a754a17f3899e3b5716f0d0497cb2470
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1621790Reviewed-by: Luciano Pacheco <lucmult@chromium.org>
Commit-Queue: François Degros <fdegros@chromium.org>
Auto-Submit: François Degros <fdegros@chromium.org>
Cr-Commit-Position: refs/heads/master@{#661978}

ui/file_manager/file_manager/background/js/volume_manager_factory.js

@@ -25,8 +25,7 @@ var volumeManagerFactory = (() => {
   async function getInstance() {
     if (!instance) {
       instance = new VolumeManagerImpl();
-      instanceInitialized =
-          new Promise(fulfill => instance.initialize(fulfill));
+      instanceInitialized = instance.initialize();
     }
     await instanceInitialized;
     return instance;

ui/file_manager/file_manager/background/js/volume_manager_impl.js

@@ -23,8 +23,7 @@ class VolumeManagerImpl extends cr.EventTarget {
 
     /**
      * Queue for mounting.
-     * @type {AsyncUtil.Queue}
-     * @private
+     * @private @const {AsyncUtil.Queue}
      */
     this.mountQueue_ = new AsyncUtil.Queue();
 
@@ -119,36 +118,38 @@ class VolumeManagerImpl extends cr.EventTarget {
 
   /**
    * Initializes mount points.
-   * @param {function()} callback Called upon the completion of the
-   *     initialization.
+   * @return {!Promise<void>}
    */
-  initialize(callback) {
-    chrome.fileManagerPrivate.onMountCompleted.addListener(
-        this.onMountCompleted_.bind(this));
-    console.warn('Getting volume list');
-    chrome.fileManagerPrivate.getVolumeMetadataList(volumeMetadataList => {
-      console.warn(`There are ${volumeMetadataList.length} volumes`);
-      // We must subscribe to the mount completed event in the callback of
-      // getVolumeMetadataList. crbug.com/330061.
-      // But volumes reported by onMountCompleted events must be added after the
-      // volumes in the volumeMetadataList are mounted. crbug.com/135477.
-      this.mountQueue_.run(async (inCallback) => {
-        try {
-          // Create VolumeInfo for each volume.
-          await Promise.all(volumeMetadataList.map(async (volumeMetadata) => {
-            console.warn(`Initializing volume ${volumeMetadata.volumeId}`);
-            const volumeInfo = await this.addVolumeMetadata_(volumeMetadata);
-            console.warn(`Initialized volume ${volumeInfo.volumeId}`);
-          }));
-
-          console.warn('Initialized all volumes');
-        } finally {
-          // Call the callback of the initialize function.
-          callback();
-          // Call the callback of AsyncQueue. Maybe it invokes callbacks
-          // registered by mountCompleted events.
-          inCallback();
-        }
+  initialize() {
+    return new Promise((resolve, reject) => {
+      chrome.fileManagerPrivate.onMountCompleted.addListener(
+          this.onMountCompleted_.bind(this));
+      console.warn('Getting volume list');
+      chrome.fileManagerPrivate.getVolumeMetadataList(volumeMetadataList => {
+        console.warn(`There are ${volumeMetadataList.length} volumes`);
+        // We must subscribe to the mount completed event in the callback of
+        // getVolumeMetadataList (crbug.com/330061). But volumes reported by
+        // onMountCompleted events must be added after the volumes in the
+        // volumeMetadataList are mounted (crbug.com/135477).
+        this.mountQueue_.run(async (done) => {
+          try {
+            // Create VolumeInfo for each volume.
+            await Promise.all(volumeMetadataList.map(async (volumeMetadata) => {
+              console.warn(`Initializing volume ${volumeMetadata.volumeId}`);
+              const volumeInfo = await this.addVolumeMetadata_(volumeMetadata);
+              console.warn(`Initialized volume ${volumeInfo.volumeId}`);
+            }));
+
+            console.warn('Initialized all volumes');
+            resolve();
+          } catch (e) {
+            reject(e);
+          } finally {
+            // Call the callback of AsyncQueue. Maybe it invokes callbacks
+            // registered by mountCompleted events.
+            done();
+          }
+        });
       });
     });
   }
@@ -160,7 +161,7 @@ class VolumeManagerImpl extends cr.EventTarget {
    * @private
    */
   onMountCompleted_(event) {
-    this.mountQueue_.run(async (callback) => {
+    this.mountQueue_.run(async (done) => {
       try {
         switch (event.eventType) {
           case 'mount':
@@ -212,7 +213,7 @@ class VolumeManagerImpl extends cr.EventTarget {
             break;
         }
       } finally {
-        callback();
+        done();
       }
     });
   }