sync: Add pre-commit update avoidance mode + flag

sync/sessions/sync_session_unittest.cc

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "sync/sessions/sync_session.h"
 
 #include "base/compiler_specific.h"
 #include "base/location.h"
 #include "base/memory/ref_counted.h"
 #include "base/message_loop.h"
@@ skipping 47 matching lines @@
     context_.reset(
         new SyncSessionContext(
             NULL,
             NULL,
             workers,
             &extensions_activity_monitor_,
             std::vector<SyncEngineEventListener*>(),
             NULL,
             NULL,
             true,  // enable keystore encryption
+            false,  // force enable pre-commit GU avoidance experiment
             "fake_invalidator_client_id"));
     context_->set_routing_info(routes_);
 
     session_.reset(MakeSession());
   }
   virtual void TearDown() {
     session_.reset();
     context_.reset();
   }
 
@@ skipping 117 matching lines @@
 
   ASSERT_EQ(3U, invalidation_map.size());
   EXPECT_EQ(invalidation_map[BOOKMARKS].payload, payload);
   EXPECT_EQ(invalidation_map[PASSWORDS].payload, payload);
   EXPECT_EQ(invalidation_map[AUTOFILL].payload, payload);
 }
 
 }  // namespace
 }  // namespace sessions
 }  // namespace syncer