Mark flaky chrome_public tests with @RetryOnFailure Batch 6

chrome/android/javatests/src/org/chromium/chrome/browser/webapps/WebappModeTest.java

Index: chrome/android/javatests/src/org/chromium/chrome/browser/webapps/WebappModeTest.java
diff --git a/chrome/android/javatests/src/org/chromium/chrome/browser/webapps/WebappModeTest.java b/chrome/android/javatests/src/org/chromium/chrome/browser/webapps/WebappModeTest.java
index a3e0cb8d1eae1fc9417cf322e37f96493afb829e..74696efd1a7b55857dfe25930f92cff1dbd81238 100644
--- a/chrome/android/javatests/src/org/chromium/chrome/browser/webapps/WebappModeTest.java
+++ b/chrome/android/javatests/src/org/chromium/chrome/browser/webapps/WebappModeTest.java
@@ -14,6 +14,7 @@ import android.view.View;
 import org.chromium.base.ApplicationStatus;
 import org.chromium.base.ContextUtils;
 import org.chromium.base.ThreadUtils;
+import org.chromium.base.test.util.RetryOnFailure;
 import org.chromium.base.test.util.UrlUtils;
 import org.chromium.blink_public.platform.WebDisplayMode;
 import org.chromium.chrome.browser.ChromeActivity;
@@ -41,6 +42,7 @@ import org.chromium.content_public.common.ScreenOrientationValues;
  * FLAG_ACTIVITY_NEW_DOCUMENT mechanism.  Moreover, we don't have access to the task list pre-L so
  * we have to assume that any non-running WebappActivities are not listed in Android's Overview.
  */
+@RetryOnFailure
 public class WebappModeTest extends MultiActivityTestBase {
     private static final String WEBAPP_1_ID = "webapp_id_1";
     private static final String WEBAPP_1_URL = UrlUtils.encodeHtmlDataUri(