Persist Directory to disk when the app is backgrounded.

chrome/android/sync_shell/javatests/src/chromium/chrome/browser/sync/SyncTest.java

Index: chrome/android/sync_shell/javatests/src/chromium/chrome/browser/sync/SyncTest.java
diff --git a/chrome/android/sync_shell/javatests/src/chromium/chrome/browser/sync/SyncTest.java b/chrome/android/sync_shell/javatests/src/chromium/chrome/browser/sync/SyncTest.java
index 823403682ae3899ac295f6c7da8e6d1d491d6da0..6a62722091baaac147d73c273535212903f129a5 100644
--- a/chrome/android/sync_shell/javatests/src/chromium/chrome/browser/sync/SyncTest.java
+++ b/chrome/android/sync_shell/javatests/src/chromium/chrome/browser/sync/SyncTest.java
@@ -9,6 +9,8 @@ import android.app.Activity;
 import android.test.suitebuilder.annotation.LargeTest;
 import android.util.Log;
 
+import org.chromium.base.ActivityState;
+import org.chromium.base.ApplicationStatus;
 import org.chromium.base.ThreadUtils;
 import org.chromium.base.test.util.Feature;
 import org.chromium.chrome.browser.identity.UniqueIdentificationGenerator;
@@ -103,6 +105,22 @@ public class SyncTest extends ChromeShellTestBase {
 
     @LargeTest
     @Feature({"Sync"})
+    public void testFlushDirectoryDoesntBreakSync() throws Throwable {
+        setupTestAccountAndSignInToSync(FOREIGN_SESSION_TEST_MACHINE_ID);
+        final Activity activity = getActivity();
+
+        runTestOnUiThread(new Runnable() {
+            @Override
+            public void run() {
+                ApplicationStatus.onStateChangeForTesting(activity, ActivityState.PAUSED);
+            }
+        });
+
+        // TODO(pvalenzuela): When available, check that sync is still functional.
+    }
+
+    @LargeTest
+    @Feature({"Sync"})
     public void testAboutSyncPageDisplaysCurrentSyncStatus() throws InterruptedException {
         setupTestAccountAndSignInToSync(FOREIGN_SESSION_TEST_MACHINE_ID);