Disabling UndoTabModelTest#testAddTab due to flakiness

chrome/android/javatests/src/org/chromium/chrome/browser/tabmodel/UndoTabModelTest.java

Index: chrome/android/javatests/src/org/chromium/chrome/browser/tabmodel/UndoTabModelTest.java
diff --git a/chrome/android/javatests/src/org/chromium/chrome/browser/tabmodel/UndoTabModelTest.java b/chrome/android/javatests/src/org/chromium/chrome/browser/tabmodel/UndoTabModelTest.java
index 22f0f59835dea47f3ba1833c2af3f738a53f50e3..311488bc85ceef88fc4ae5d273021ced19d8c1b6 100644
--- a/chrome/android/javatests/src/org/chromium/chrome/browser/tabmodel/UndoTabModelTest.java
+++ b/chrome/android/javatests/src/org/chromium/chrome/browser/tabmodel/UndoTabModelTest.java
@@ -1313,8 +1313,10 @@ public class UndoTabModelTest extends ChromeTabbedActivityTestBase {
      * 8.  CreateTab(5)               [ 5s ]             -                 [ 5s ]
      * @throws InterruptedException
      */
-    @MediumTest
-    @Restriction(ChromeRestriction.RESTRICTION_TYPE_PHONE) // See crbug.com/633607
+    //@MediumTest
+    //@Restriction(ChromeRestriction.RESTRICTION_TYPE_PHONE) // See crbug.com/633607
+    // Disabled due to flakiness on linux_android_rel_ng (crbug.com/661429)
+    @DisabledTest
     public void testAddTab() throws InterruptedException {
         TabModel model = getActivity().getTabModelSelector().getModel(false);
         ChromeTabCreator tabCreator = getActivity().getTabCreator(false);