Download home v2: Fix issue in storage summary.

Currently removing an ongoing download may hit assertion in
StorageSummaryProvider, this is due to a bug in onItemUpdated that we
increase the total storage based on old item instead of the new item.

Bug: 892328
Change-Id: I64cda81662290df049f74aa3f1893c7a0984c043
Reviewed-on: https://chromium-review.googlesource.com/c/1284705Reviewed-by: Shakti Sahu <shaktisahu@chromium.org>
Commit-Queue: Xing Liu <xingliu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#600167}

chrome/android/java/src/org/chromium/chrome/browser/download/home/storage/StorageSummaryProvider.java

@@ -96,7 +96,7 @@ public class StorageSummaryProvider implements OfflineItemFilterObserver {
     public void onItemUpdated(OfflineItem oldItem, OfflineItem item) {
         // Computes the delta of storage used by downloads.
         mTotalDownloadSize -= oldItem.receivedBytes;
-        mTotalDownloadSize += oldItem.receivedBytes;
+        mTotalDownloadSize += item.receivedBytes;
 
         if (item.state != OfflineItemState.IN_PROGRESS) update();
     }