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

sync/api/sync_change_processor.h

Index: sync/api/sync_change_processor.h
diff --git a/sync/api/sync_change_processor.h b/sync/api/sync_change_processor.h
index d97d28d6b41fae4395fd55e177b89b5e4b9ae18e..31788e2aa86ac1cfbe82831f1d68b9603b151ec4 100644
--- a/sync/api/sync_change_processor.h
+++ b/sync/api/sync_change_processor.h
@@ -10,12 +10,14 @@
 
 #include "sync/api/sync_error.h"
 
-class SyncChange;
-
 namespace tracked_objects {
 class Location;
 }  // namespace tracked_objects
 
+namespace csync {
+
+class SyncChange;
+
 typedef std::vector<SyncChange> SyncChangeList;
 
 // An interface for services that handle receiving SyncChanges.
@@ -36,4 +38,6 @@ class SyncChangeProcessor {
       const SyncChangeList& change_list) = 0;
 };
 
+}  // namespace csync
+
 #endif  // SYNC_API_SYNC_CHANGE_PROCESSOR_H_