[Sync] Move sync/{internal_api,syncable} into syncer namespace

sync/test/engine/mock_connection_manager.h

Index: sync/test/engine/mock_connection_manager.h
diff --git a/sync/test/engine/mock_connection_manager.h b/sync/test/engine/mock_connection_manager.h
index 1fe264edf37bd7b8f40f6732a2fc3f302fa00b94..c787027b787279948a61da866b0101aa76beb593 100644
--- a/sync/test/engine/mock_connection_manager.h
+++ b/sync/test/engine/mock_connection_manager.h
@@ -21,6 +21,8 @@
 #include "sync/internal_api/public/syncable/model_type_payload_map.h"
 #include "sync/protocol/sync.pb.h"
 
+namespace syncer {
+
 class MockConnectionManager : public syncer::ServerConnectionManager {
  public:
   class MidCommitObserver {
@@ -348,4 +350,6 @@ class MockConnectionManager : public syncer::ServerConnectionManager {
   DISALLOW_COPY_AND_ASSIGN(MockConnectionManager);
 };
 
+}  // namespace syncer
+
 #endif  // SYNC_TEST_ENGINE_MOCK_CONNECTION_MANAGER_H_