Mark two InvalidationPreferenceTest to be flaky.

Flaky tests:
org.chromium.components.sync.notifier.InvalidationPreferencesTest.testReadWriteAndReadData
org.chromium.components.sync.notifier.InvalidationPreferencesTest.testReadWriteAndReadData

Bug: 905233
Change-Id: Iad0e641c19adf4d21eb37f2642d104537fdc2f48
Reviewed-on: https://chromium-review.googlesource.com/c/1337331
Commit-Queue: Arthur Sonzogni <arthursonzogni@chromium.org>
Reviewed-by: Marc Treib <treib@chromium.org>
Cr-Commit-Position: refs/heads/master@{#608308}

components/sync/android/javatests/src/org/chromium/components/sync/notifier/InvalidationPreferencesTest.java

@@ -17,6 +17,7 @@ import org.chromium.base.ApiCompatibilityUtils;
 import org.chromium.base.CollectionUtil;
 import org.chromium.base.test.BaseJUnit4ClassRunner;
 import org.chromium.base.test.util.Feature;
+import org.chromium.base.test.util.FlakyTest;
 import org.chromium.base.test.util.RetryOnFailure;
 
 import java.util.Arrays;
@@ -31,6 +32,7 @@ import java.util.Set;
 @RetryOnFailure
 public class InvalidationPreferencesTest {
     @Test
+    @FlakyTest(message = "https://crbug.com/905233")
     @SmallTest
     @Feature({"Sync"})
     public void testReadMissingData() {
@@ -45,6 +47,7 @@ public class InvalidationPreferencesTest {
     }
 
     @Test
+    @FlakyTest(message = "https://crbug.com/905233")
     @SmallTest
     @Feature({"Sync"})
     public void testReadWriteAndReadData() {