[Sync] Put everything in sync/api into csync namespace

sync/api/sync_error_unittest.cc

Index: sync/api/sync_error_unittest.cc
diff --git a/sync/api/sync_error_unittest.cc b/sync/api/sync_error_unittest.cc
index c700db5594c53dc38f523602c701858d5b978b33..28fe2b61f8ecde46043267996d0127f0bb378bb2 100644
--- a/sync/api/sync_error_unittest.cc
+++ b/sync/api/sync_error_unittest.cc
@@ -9,6 +9,8 @@
 #include "base/location.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
+namespace csync {
+
 using std::string;
 using syncable::ModelType;
 
@@ -130,3 +132,5 @@ TEST_F(SyncErrorTest, ToString) {
 }
 
 }  // namespace
+
+}  // namespace csync