Fix localstorage data migration.

content/browser/dom_storage/local_storage_context_mojo.cc

 // Copyright 2016 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 "content/browser/dom_storage/local_storage_context_mojo.h"
 
 #include "base/memory/ptr_util.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/strings/string_number_conversions.h"
 #include "components/leveldb/public/cpp/util.h"
@@ skipping 52 matching lines @@
   key.reserve(arraysize(kMetaPrefix) + serialized_origin.size());
   key.insert(key.end(), kMetaPrefix, kMetaPrefix + arraysize(kMetaPrefix));
   key.insert(key.end(), serialized_origin.begin(), serialized_origin.end());
   return key;
 }
 
 void NoOpSuccess(bool success) {}
 
 std::vector<uint8_t> String16ToUint8Vector(const base::string16& input) {
   const uint8_t* data = reinterpret_cast<const uint8_t*>(input.data());
-  return std::vector<uint8_t>(data, data + input.size() * sizeof(base::char16));
+  std::vector<uint8_t> result;
+  result.reserve(input.size() * sizeof(base::char16) + 1);
+  result.push_back(0);

[michaeln, 2017/03/22 23:49:51]

The magic "0" value here is pretty magical, it might be worth sharing a function
or a symbol for the value somewhere in common\dom_storage, or short of that,
even duplicating the enum class here. I see the test would pick up a failure in
a future format change, but some breadcrumbs (or compiler errors) might help
more quickly.

[Marijn Kruisselbrink, 2017/03/31 23:06:14]

Yeah, I agree that this isn't very nice. I changed it to at least give the
number a name. Moving to common/dom_storage is something I'd rather not do, as
ultimately the renderer side code should move into blink, so wouldn't be able to
use content/common anyway.

+  result.insert(result.end(), data, data + input.size() * sizeof(base::char16));
+  return result;
 }
 
 void MigrateStorageHelper(
     base::FilePath db_path,
     const scoped_refptr<base::SingleThreadTaskRunner> reply_task_runner,
     base::Callback<void(std::unique_ptr<LevelDBWrapperImpl::ValueMap>)>
         callback) {
   DOMStorageDatabase db(db_path);
   DOMStorageValuesMap map;
   db.ReadAllValues(&map);
@@ skipping 505 matching lines @@
   for (const auto& info : usage) {
     url::Origin origin_candidate(info.origin);
     if (!origin_candidate.IsSameOriginWith(origin) &&
         origin_candidate.IsSamePhysicalOriginWith(origin))
       DeleteStorage(origin_candidate);
   }
   DeleteStorage(origin);
 }
 
 }  // namespace content