Mark NewTabPageTest#testRender_SignInPromoWithAccount as flaky.

Bug: 1155107
Change-Id: Ia0fe38242513ba5e0d6c5fd67b984bab5a3dd2b0
TBR: triploblastic@chromium.org
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2574955Reviewed-by: Balazs Engedy <engedy@chromium.org>
Commit-Queue: Balazs Engedy <engedy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#834674}

chrome/android/javatests/src/org/chromium/chrome/browser/ntp/NewTabPageTest.java

@@ -200,6 +200,7 @@ public class NewTabPageTest {
     @SmallTest
     @Feature({"NewTabPage", "FeedNewTabPage", "RenderTest"})
     @Features.EnableFeatures(ChromeFeatureList.MOBILE_IDENTITY_CONSISTENCY)
+    @FlakyTest(message = "https://crbug.com/1155107")
     public void testRender_SignInPromoWithAccount() throws Exception {
         mAccountManagerTestRule.addAccount(mAccountManagerTestRule.createProfileDataFromName(
                 AccountManagerTestRule.TEST_ACCOUNT_EMAIL));