Add unit tests for the 'disable-sync' flag

chrome/browser/sync/profile_sync_service_unittest.cc

Index: chrome/browser/sync/profile_sync_service_unittest.cc
diff --git a/chrome/browser/sync/profile_sync_service_unittest.cc b/chrome/browser/sync/profile_sync_service_unittest.cc
index 566b369a86dd44086231c8da801d032934d239bc..044542c8ce508280bc382a319c0a565562cb26ea 100644
--- a/chrome/browser/sync/profile_sync_service_unittest.cc
+++ b/chrome/browser/sync/profile_sync_service_unittest.cc
@@ -639,5 +639,16 @@ TEST_F(ProfileSyncServiceTest, ClearLastSyncedTimeOnSignOut) {
             service()->GetLastSyncedTimeString());
 }
 
+// Verify that the disable sync flag disables sync.
+TEST_F(ProfileSyncServiceTest, DisableSyncFlag) {
+  base::CommandLine::ForCurrentProcess()->AppendSwitch(switches::kDisableSync);
+  EXPECT_FALSE(ProfileSyncService::IsSyncEnabled());
+}
+
+// Verify that no disable sync flag enables sync.
+TEST_F(ProfileSyncServiceTest, NoDisableSyncFlag) {
+  EXPECT_TRUE(ProfileSyncService::IsSyncEnabled());
+}
+
 }  // namespace
 }  // namespace browser_sync