sync: Add ControlPreference protobuf and supporting code

sync/internal_api/sync_manager_impl_unittest.cc

Index: sync/internal_api/sync_manager_impl_unittest.cc
diff --git a/sync/internal_api/sync_manager_impl_unittest.cc b/sync/internal_api/sync_manager_impl_unittest.cc
index b4ca259b301edf2d78fdcfd520bfb0ca55a43290..9c6c77a05b539b97068eaf4203338b95dc69669f 100644
--- a/sync/internal_api/sync_manager_impl_unittest.cc
+++ b/sync/internal_api/sync_manager_impl_unittest.cc
@@ -858,6 +858,7 @@ class SyncManagerTest : public testing::Test,
     (*out)[NIGORI] = GROUP_PASSIVE;
     (*out)[DEVICE_INFO] = GROUP_PASSIVE;
     (*out)[EXPERIMENTS] = GROUP_PASSIVE;
+    (*out)[CONTROL_PREFERENCES] = GROUP_PASSIVE;
     (*out)[BOOKMARKS] = GROUP_PASSIVE;
     (*out)[THEMES] = GROUP_PASSIVE;
     (*out)[SESSIONS] = GROUP_PASSIVE;
@@ -1247,7 +1248,7 @@ TEST_F(SyncManagerTest, GetChildNodeIds) {
   const ListValue* nodes = NULL;
   ASSERT_TRUE(return_args.Get().GetList(0, &nodes));
   ASSERT_TRUE(nodes);
-  EXPECT_EQ(8u, nodes->GetSize());
+  EXPECT_EQ(9u, nodes->GetSize());
 }
 
 TEST_F(SyncManagerTest, GetChildNodeIdsFailure) {