Fix an NPE as DownloadManager.query() could return a null cursor

chrome/android/java/src/org/chromium/chrome/browser/download/DownloadManagerDelegate.java

Index: chrome/android/java/src/org/chromium/chrome/browser/download/DownloadManagerDelegate.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/download/DownloadManagerDelegate.java b/chrome/android/java/src/org/chromium/chrome/browser/download/DownloadManagerDelegate.java
index 8c461ea661348cb0dc9beec9afe5aedea54493b6..99ea10f812b896e9f92591e9164a3888c287f4f7 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/download/DownloadManagerDelegate.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/download/DownloadManagerDelegate.java
@@ -98,6 +98,10 @@ public class DownloadManagerDelegate {
                     (DownloadManager) mContext.getSystemService(Context.DOWNLOAD_SERVICE);
             Cursor c = manager.query(
                     new DownloadManager.Query().setFilterById(mDownloadItem.getSystemDownloadId()));
+            if (c == null) {
+                return new DownloadQueryResult(mDownloadItem,
+                        DownloadManagerService.DOWNLOAD_STATUS_CANCELLED, 0, 0, false, 0);
+            }
             long bytesDownloaded = 0;
             boolean canResolve = false;
             int downloadStatus = DownloadManagerService.DOWNLOAD_STATUS_IN_PROGRESS;