[Sync] Rename csync namespace to syncer

sync/api/sync_error_unittest.cc

 // Copyright (c) 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/api/sync_error.h"
 
 #include <string>
 
 #include "base/location.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
-namespace csync {
+namespace syncer {
 
 using std::string;
 using syncable::ModelType;
 
 namespace {
 
 typedef testing::Test SyncErrorTest;
 
 TEST_F(SyncErrorTest, Unset) {
   SyncError error;
@@ skipping 103 matching lines @@
   EXPECT_FALSE(error2.IsSet());
   EXPECT_EQ(std::string(), error2.ToString());
 
   error2 = error;
   EXPECT_TRUE(error2.IsSet());
   EXPECT_NE(string::npos, error.ToString().find(expected));
 }
 
 }  // namespace
 
-}  // namespace csync
+}  // namespace syncer