Files App: Replaced some var with const or let

BUG=chromium:912236
TEST=browser_tests --gtest_filter="*/FilesApp*"

Change-Id: I0ea62bb92376ab0ee68aef2a76ab9594c45cf341
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2303932Reviewed-by: Jeremie Boulic <jboulic@chromium.org>
Commit-Queue: François Degros <fdegros@chromium.org>
Cr-Commit-Position: refs/heads/master@{#789382}

ui/file_manager/base/js/filtered_volume_manager.js

@@ -170,7 +170,7 @@ class FilteredVolumeManager extends cr.EventTarget {
 
     // Cache volumeInfoList.
     const volumeInfoList = [];
-    for (var i = 0; i < this.volumeManager_.volumeInfoList.length; i++) {
+    for (let i = 0; i < this.volumeManager_.volumeInfoList.length; i++) {
       const volumeInfo = this.volumeManager_.volumeInfoList.item(i);
       // TODO(hidehiko): Filter mounted volumes located on Drive File System.
       if (!this.isAllowedVolume_(volumeInfo)) {
@@ -244,24 +244,24 @@ class FilteredVolumeManager extends cr.EventTarget {
   onVolumeInfoListUpdated_(event) {
     // Filters some volumes.
     let index = event.index;
-    for (var i = 0; i < event.index; i++) {
-      var volumeInfo = this.volumeManager_.volumeInfoList.item(i);
+    for (let i = 0; i < event.index; i++) {
+      const volumeInfo = this.volumeManager_.volumeInfoList.item(i);
       if (!this.isAllowedVolume_(volumeInfo)) {
         index--;
       }
     }
 
     let numRemovedVolumes = 0;
-    for (var i = 0; i < event.removed.length; i++) {
-      var volumeInfo = event.removed[i];
+    for (let i = 0; i < event.removed.length; i++) {
+      const volumeInfo = event.removed[i];
       if (this.isAllowedVolume_(volumeInfo)) {
         numRemovedVolumes++;
       }
     }
 
     const addedVolumes = [];
-    for (var i = 0; i < event.added.length; i++) {
-      var volumeInfo = event.added[i];
+    for (let i = 0; i < event.added.length; i++) {
+      const volumeInfo = event.added[i];
       if (this.isAllowedVolume_(volumeInfo)) {
         addedVolumes.push(volumeInfo);
       }

ui/file_manager/file_manager/background/js/mock_volume_manager.js

@@ -104,9 +104,9 @@ class MockVolumeManager {
     }
 
     if (entry.filesystem.name === VolumeManagerCommon.VolumeType.DRIVE) {
-      var volumeInfo = this.volumeInfoList.item(0);
-      var rootType = VolumeManagerCommon.RootType.DRIVE;
-      var isRootEntry = entry.fullPath === '/root';
+      const volumeInfo = this.volumeInfoList.item(0);
+      let rootType = VolumeManagerCommon.RootType.DRIVE;
+      let isRootEntry = entry.fullPath === '/root';
       if (entry.fullPath.startsWith('/team_drives')) {
         if (entry.fullPath === '/team_drives') {
           rootType = VolumeManagerCommon.RootType.SHARED_DRIVES_GRAND_ROOT;
@@ -127,10 +127,10 @@ class MockVolumeManager {
       return new EntryLocationImpl(volumeInfo, rootType, isRootEntry, true);
     }
 
-    volumeInfo = this.getVolumeInfo(entry);
-    rootType =
+    const volumeInfo = this.getVolumeInfo(entry);
+    const rootType =
         VolumeManagerCommon.getRootTypeFromVolumeType(volumeInfo.volumeType);
-    isRootEntry = util.isSameEntry(entry, volumeInfo.fileSystem.root);
+    const isRootEntry = util.isSameEntry(entry, volumeInfo.fileSystem.root);
     return new EntryLocationImpl(volumeInfo, rootType, isRootEntry, false);
   }