Minor code / comment fixes for drive_sync_handler_unittest

 - update the comments to match what the actually code does
 - check progress center item state like other unittests do

No change in test behavior.

Bug: 907964
Tbr: slangley
No-try: true
Change-Id: I8f307b699d5005cbdefe346d838088610c9f88cf
Reviewed-on: https://chromium-review.googlesource.com/c/1352072Reviewed-by: Noel Gordon <noel@chromium.org>
Commit-Queue: Noel Gordon <noel@chromium.org>
Cr-Commit-Position: refs/heads/master@{#611065}

ui/file_manager/file_manager/background/js/drive_sync_handler_unittest.js

@@ -118,7 +118,7 @@ function testUniqueErrorIds() {
     fileUrl: '',
   });
 
-  // Check that this created second item.
+  // Check that this created a second item.
   assertEquals(2, progressCenter.getItemCount());
 }
 
@@ -139,7 +139,7 @@ function testErrorDedupe() {
     fileUrl: '',
   });
 
-  // Check that this created second item.
+  // Check that this did not create a second item.
   assertEquals(1, progressCenter.getItemCount());
 }
 
@@ -157,14 +157,16 @@ function testOffline() {
 
   // Check that this created one item.
   assertEquals(1, progressCenter.getItemCount());
-  assertEquals(
-      ProgressItemState.PROGRESSING, progressCenter.items['drive-sync'].state);
+  var item = progressCenter.items['drive-sync'];
+  assertEquals(ProgressItemState.PROGRESSING, item.state);
   assertTrue(driveSyncHandler.syncing);
 
+  // Go offline.
   chrome.fileManagerPrivate.onDriveConnectionStatusChanged.listener_();
 
+  // Check that this item was cancelled.
   assertEquals(1, progressCenter.getItemCount());
-  assertEquals(
-      ProgressItemState.CANCELED, progressCenter.items['drive-sync'].state);
+  item = progressCenter.items['drive-sync'];
+  assertEquals(ProgressItemState.CANCELED, item.state);
   assertFalse(driveSyncHandler.syncing);
 }