Mark testShow_SingleAsHomepage flaky.

TBR: gogerald@google.com
Bug: 1139515
Change-Id: I11bb4ed067a760763f96cca37d44ceab2c9794cd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2481748
Commit-Queue: Sky Malice <skym@chromium.org>
Reviewed-by: Sky Malice <skym@chromium.org>
Cr-Commit-Position: refs/heads/master@{#818455}

chrome/android/features/start_surface/internal/javatests/src/org/chromium/chrome/features/start_surface/StartSurfaceTest.java

@@ -70,6 +70,7 @@ import org.chromium.base.test.util.CommandLineFlags;
 import org.chromium.base.test.util.DisableIf;
 import org.chromium.base.test.util.DisabledTest;
 import org.chromium.base.test.util.Feature;
+import org.chromium.base.test.util.FlakyTest;
 import org.chromium.base.test.util.Restriction;
 import org.chromium.chrome.browser.ChromeTabbedActivity;
 import org.chromium.chrome.browser.DeferredStartupHandler;
@@ -373,6 +374,7 @@ public class StartSurfaceTest {
     @MediumTest
     @Feature({"StartSurface"})
     @CommandLineFlags.Add({BASE_PARAMS + "/single"})
+    @FlakyTest(message = "https://crbug.com/1139515")
     public void testShow_SingleAsHomepage() {
         if (!mImmediateReturn) {
             onView(withId(org.chromium.chrome.tab_ui.R.id.home_button)).perform(click());