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

sync/engine/build_commit_command.h

Index: sync/engine/build_commit_command.h
diff --git a/sync/engine/build_commit_command.h b/sync/engine/build_commit_command.h
index d72765b226b4a64ef8016961b60f26fed90f6a81..b7dbee0b3004c02564e3467f512203082ed10e79 100644
--- a/sync/engine/build_commit_command.h
+++ b/sync/engine/build_commit_command.h
@@ -13,16 +13,16 @@
 #include "sync/engine/syncproto.h"
 #include "sync/syncable/entry_kernel.h"
 
-namespace syncable {
-class Entry;
-}
-
 namespace syncer {
 
 namespace sessions {
 class OrderedCommitSet;
 }
 
+namespace syncable {
+class Entry;
+}
+
 // A class that contains the code used to serialize a set of sync items into a
 // protobuf commit message.  This conversion process references the
 // syncable::Directory, which is why it must be called within the same