Configure Drive's shortcuts virtual folder

BUG=b:148900751

Change-Id: I50cde41f63aa8b9bba2be609665ba48fb28ba083
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2040499
Commit-Queue: Sergei Datsenko <dats@chromium.org>
Reviewed-by: Luciano Pacheco <lucmult@chromium.org>
Reviewed-by: Alex Danilo <adanilo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#738849}

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

@@ -400,6 +400,15 @@ class VolumeManagerImpl extends cr.EventTarget {
         // read-write.
         isReadOnly = entry.fullPath.split('/').length < 4;
         isRootEntry = entry.fullPath === '/.files-by-id';
+      } else if (
+          entry.fullPath === '/.shortcut-targets-by-id' ||
+          entry.fullPath.indexOf('/.shortcut-targets-by-id/') === 0) {
+        rootType = VolumeManagerCommon.RootType.DRIVE_OTHER;
+
+        // /.shortcut-targets-by-id/<id> is read-only, but
+        // /.shortcut-targets-by-id/<id>/foo is read-write.
+        isReadOnly = entry.fullPath.split('/').length < 4;
+        isRootEntry = entry.fullPath === '/.shortcut-targets-by-id';
       } else {
         // Accessing Drive files outside of /drive/root and /drive/other is not
         // allowed, but can happen. Therefore returning null.

ui/file_manager/file_manager/background/js/volume_manager_unittest.js

@@ -326,6 +326,33 @@ function testGetLocationInfo(callback) {
         assertFalse(driveFilesByIdLocationInfo.isReadOnly);
         assertFalse(driveFilesByIdLocationInfo.isRootEntry);
 
+        const driveShortcutTargetsByIdDirectoryEntry =
+            MockDirectoryEntry.create(
+                new MockFileSystem('drive:drive-foobar%40chromium.org-hash'),
+                '/.shortcut-targets-by-id/abcdef');
+        const driveShortcutTargetsByIdDirectoryLocationInfo =
+            volumeManager.getLocationInfo(
+                driveShortcutTargetsByIdDirectoryEntry);
+        assertEquals(
+            VolumeManagerCommon.RootType.DRIVE_OTHER,
+            driveShortcutTargetsByIdDirectoryLocationInfo.rootType);
+        assertFalse(
+            driveShortcutTargetsByIdDirectoryLocationInfo.hasFixedLabel);
+        assertTrue(driveShortcutTargetsByIdDirectoryLocationInfo.isReadOnly);
+        assertFalse(driveShortcutTargetsByIdDirectoryLocationInfo.isRootEntry);
+
+        const driveShortcutTargetsByIdEntry = MockDirectoryEntry.create(
+            new MockFileSystem('drive:drive-foobar%40chromium.org-hash'),
+            '/.shortcut-targets-by-id/abcdef/foo');
+        const driveShortcutTargetsByIdLocationInfo =
+            volumeManager.getLocationInfo(driveShortcutTargetsByIdEntry);
+        assertEquals(
+            VolumeManagerCommon.RootType.DRIVE_OTHER,
+            driveShortcutTargetsByIdLocationInfo.rootType);
+        assertFalse(driveShortcutTargetsByIdLocationInfo.hasFixedLabel);
+        assertFalse(driveShortcutTargetsByIdLocationInfo.isReadOnly);
+        assertFalse(driveShortcutTargetsByIdLocationInfo.isRootEntry);
+
         const androidRoot =
             MockFileEntry.create(new MockFileSystem('android_files:0'), '/');
         const androidRootLocationInfo =