[Sync] Replacing NULL with nullptr/null throughout sync code.

chrome/browser/sync/test/integration/sync_auth_test.cc

Index: chrome/browser/sync/test/integration/sync_auth_test.cc
diff --git a/chrome/browser/sync/test/integration/sync_auth_test.cc b/chrome/browser/sync/test/integration/sync_auth_test.cc
index 9ad5d8188ec8253decf575cfdf36197ce2480802..1e7391e143c512f63acae2e8f917eb2fc840fd06 100644
--- a/chrome/browser/sync/test/integration/sync_auth_test.cc
+++ b/chrome/browser/sync/test/integration/sync_auth_test.cc
@@ -81,7 +81,7 @@ class SyncAuthTest : public SyncTest {
     int bookmark_index = GetNextBookmarkIndex();
     std::string title = base::StringPrintf("Bookmark %d", bookmark_index);
     GURL url = GURL(base::StringPrintf("http://www.foo%d.com", bookmark_index));
-    EXPECT_TRUE(AddURL(0, title, url) != NULL);
+    EXPECT_TRUE(AddURL(0, title, url) != nullptr);
 
     // Run until the bookmark is committed or an auth error is encountered.
     TestForAuthError(GetSyncService(0)).Wait();