Android: Mark testWebApkLaunchesByLauncherActivity as flaky

TBR=pkotwicz

Bug: 852648
Change-Id: I2799a73ecec82d9ceef99f0280655096ed2d3bdd
Reviewed-on: https://chromium-review.googlesource.com/1100890Reviewed-by: Jan Wilken Dörrie <jdoerrie@chromium.org>
Commit-Queue: Jan Wilken Dörrie <jdoerrie@chromium.org>
Cr-Commit-Position: refs/heads/master@{#567265}

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

@@ -19,6 +19,7 @@ import org.chromium.base.CommandLine;
 import org.chromium.base.metrics.RecordHistogram;
 import org.chromium.base.test.util.CommandLineFlags;
 import org.chromium.base.test.util.Feature;
+import org.chromium.base.test.util.FlakyTest;
 import org.chromium.base.test.util.ScalableTimeout;
 import org.chromium.chrome.browser.ChromeSwitches;
 import org.chromium.chrome.browser.DeferredStartupHandler;
@@ -116,6 +117,7 @@ public class WebApkIntegrationTest {
     @Test
     @LargeTest
     @Feature({"Webapps"})
+    @FlakyTest(message = "https://crbug.com/852648")
     public void testWebApkLaunchesByLauncherActivity() {
         String pwaRocksUrl = getUrlForHost("pwa.rocks");