Remove a bunch of DeepCopy() calls in the chrome.storage API.

chrome/browser/extensions/api/storage/setting_sync_data.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 "chrome/browser/extensions/api/storage/setting_sync_data.h"
 
 #include "base/json/json_reader.h"
 #include "base/json/json_writer.h"
 #include "sync/api/sync_data.h"
 #include "sync/protocol/app_setting_specifics.pb.h"
@@ skipping 64 matching lines @@
 
 const std::string& SettingSyncData::extension_id() const {
   return internal_->extension_id_;
 }
 
 const std::string& SettingSyncData::key() const {
   return internal_->key_;
 }
 
 const base::Value& SettingSyncData::value() const {
+  DCHECK(internal_.get()) << "value has been released";

[Devlin, 2015/05/15 21:59:07]

Should these be DCHECKing internal_->value_?

[not at google - send to devlin, 2015/05/15 23:28:30]

yes

   return *internal_->value_;
 }
 
+scoped_ptr<base::Value> SettingSyncData::PassValue() {
+  DCHECK(internal_.get()) << "value has been released";
+  return internal_->value_.Pass();
+}
+
 SettingSyncData::Internal::Internal(
     syncer::SyncChange::SyncChangeType change_type,
     const std::string& extension_id,
     const std::string& key,
     scoped_ptr<base::Value> value)
     : change_type_(change_type),
       extension_id_(extension_id),
       key_(key),
       value_(value.Pass()) {
-  DCHECK(value_.get());
+  DCHECK(value_.get()) << "value cannot be null";
 }
 
 SettingSyncData::Internal::~Internal() {}
 
 }  // namespace extensions