Revert of [Sync] Add size and crc32c to AttachmentId.

sync/api/attachments/attachment_id_unittest.cc

 // Copyright 2014 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/attachments/attachment.h"
 
 #include <string>
 
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace syncer {
 
+namespace {
+
+}  // namespace
+
 class AttachmentIdTest : public testing::Test {};
 
 TEST_F(AttachmentIdTest, Create_IsUnique) {
-  AttachmentId id1 = AttachmentId::Create(0, 0);
-  AttachmentId id2 = AttachmentId::Create(0, 0);
+  AttachmentId id1 = AttachmentId::Create();
+  AttachmentId id2 = AttachmentId::Create();
   EXPECT_NE(id1, id2);
 }
 
 TEST_F(AttachmentIdTest, OperatorEqual) {
-  AttachmentId id1 = AttachmentId::Create(0, 0);
+  AttachmentId id1 = AttachmentId::Create();
   AttachmentId id2(id1);
   EXPECT_EQ(id1, id2);
 }
 
 TEST_F(AttachmentIdTest, OperatorLess) {
-  AttachmentId id1 = AttachmentId::Create(0, 0);
+  AttachmentId id1 = AttachmentId::Create();
   EXPECT_FALSE(id1 < id1);
 
-  AttachmentId id2 = AttachmentId::Create(0, 0);
+  AttachmentId id2 = AttachmentId::Create();
   EXPECT_FALSE(id1 < id1);
 
   EXPECT_NE(id1, id2);
   if (id1 < id2) {
     EXPECT_FALSE(id2 < id1);
   } else {
     EXPECT_TRUE(id2 < id1);
   }
 }
 
 }  // namespace syncer