Implement a bag of chips for sync.

sync/engine/model_changing_syncer_command.cc

Index: sync/engine/model_changing_syncer_command.cc
diff --git a/sync/engine/model_changing_syncer_command.cc b/sync/engine/model_changing_syncer_command.cc
index 3fe6b2dc3a9f617579a17a9adf3525218301950c..919d344507e904189fe484750f4837da97778f5a 100644
--- a/sync/engine/model_changing_syncer_command.cc
+++ b/sync/engine/model_changing_syncer_command.cc
@@ -7,6 +7,7 @@
 #include "base/basictypes.h"
 #include "base/bind.h"
 #include "base/bind_helpers.h"
+#include "sync/engine/syncer_proto_util.h"
 #include "sync/sessions/status_controller.h"
 #include "sync/sessions/sync_session.h"
 
@@ -45,6 +46,12 @@ SyncerError ModelChangingSyncerCommand::ExecuteImpl(
       result = this_worker_result;
   }
 
+  if (result == SYNCER_OK) {
+    // In case of success, persist an eventul bag of chips.
+    SyncerProtoUtil::PersistBagOfChips(session->context()->directory(),

[Nicolas Zea, 2012/09/07 18:38:43]

we actually want to be able to persist the bag of chips even if the request
failed (it's still useful to let the server track client state even if it's
throttling for example)

Additionally, this is getting run on every command, and there are reallly only
two commands that interact with the sync server. I'd rather have this call
explicitly in those two commands.

[qsr, 2012/09/10 08:12:37]

 And I was missing one of the 2. Thanks.

 On the other hand, to have this work, I have to override the ExecuteImpl method
-> The other method is called one for each worker... Which mean that it doesn't
work if there is no worker (won't happen I guess, but still), but will be called
more than once if there is more than one worker.

+        session->status_controller().updates_response());
+  }
+
   return result;
 }