[Sync] Add cookie jar mismatch logging

sync/test/fake_server/fake_server.h

Index: sync/test/fake_server/fake_server.h
diff --git a/sync/test/fake_server/fake_server.h b/sync/test/fake_server/fake_server.h
index 21fb9635e63f3ad8e7a6ef3b2188fb39062acd9f..0f6e321ebb3228e4a001f7310b2f6276fab344c0 100644
--- a/sync/test/fake_server/fake_server.h
+++ b/sync/test/fake_server/fake_server.h
@@ -51,6 +51,12 @@ class FakeServer {
                      int* response_code,
                      std::string* response);
 
+  // Helpers for fetching the last Commit or GetUpdates messages, respectively.
+  // Returns true if the specified message existed, and false if no message has
+  // been received.
+  bool GetLastCommitMessage(sync_pb::ClientToServerMessage* message);
+  bool GetLastGetUpdatesMessage(sync_pb::ClientToServerMessage* message);
+
   // Creates a DicionaryValue representation of all entities present in the
   // server. The dictionary keys are the strings generated by ModelTypeToString
   // and the values are ListValues containing StringValue versions of entity
@@ -246,6 +252,10 @@ class FakeServer {
   // on every request. This is used to simulate a network failure on the client.
   bool network_enabled_;
 
+  // The last received client to server messages.
+  sync_pb::ClientToServerMessage last_commit_message_;
+  sync_pb::ClientToServerMessage last_getupdates_message_;
+
   // Used to verify that FakeServer is only used from one thread.
   base::ThreadChecker thread_checker_;