remove unnecessary thread hopping when updating Download notifications

chrome/android/javatests/src/org/chromium/chrome/browser/download/SystemDownloadNotifierTest.java

Index: chrome/android/javatests/src/org/chromium/chrome/browser/download/SystemDownloadNotifierTest.java
diff --git a/chrome/android/javatests/src/org/chromium/chrome/browser/download/SystemDownloadNotifierTest.java b/chrome/android/javatests/src/org/chromium/chrome/browser/download/SystemDownloadNotifierTest.java
index f2a27bb2b43fbc52d6421f3eecd2e34dfe944b34..150463763c1f26e91058219e30025919d26061bb 100644
--- a/chrome/android/javatests/src/org/chromium/chrome/browser/download/SystemDownloadNotifierTest.java
+++ b/chrome/android/javatests/src/org/chromium/chrome/browser/download/SystemDownloadNotifierTest.java
@@ -46,6 +46,16 @@ public class SystemDownloadNotifierTest extends InstrumentationTestCase {
                 final SystemDownloadNotifier.PendingNotificationInfo notificationInfo,
                 final int notificationId) {
         }
+
+        @Override
+        void updateDownloadNotification(final PendingNotificationInfo notificationInfo) {
+            ThreadUtils.runOnUiThreadBlocking(new Runnable() {
+                @Override
+                public void run() {
+                    MockSystemDownloadNotifier.super.updateDownloadNotification(notificationInfo);
+                }
+            });
+        }
     }
 
     @Override