Reland "AppCache: Add padding to cross-origin responses."

This is a reland of 85b389caa7d725cdd31f59e9a2b79ff54804b7b7

Initialized CacheRecord::padding_size to 0.

Original change's description:
> AppCache: Add padding to cross-origin responses.
>
> Bug: 918293
> Change-Id: I4f16640f06feac009d6bbbb624951da6d2669f6c
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1488059
> Commit-Queue: Staphany Park <staphany@chromium.org>
> Reviewed-by: Victor Costan <pwnall@chromium.org>
> Reviewed-by: Marijn Kruisselbrink <mek@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#644624}

Bug: 918293
Change-Id: Ie1d3f99c7e8a854d33255a4d66243da2ce16441c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1539906
Reviewed-by: Victor Costan <pwnall@chromium.org>
Commit-Queue: Staphany Park <staphany@chromium.org>
Cr-Commit-Position: refs/heads/master@{#644719}
void AppCache::InitializeWithDatabaseRecords(
    const AppCacheDatabase::CacheRecord& cache_record,
    const std::vector<AppCacheDatabase::EntryRecord>& entries,
     const std::vector<AppCacheDatabase::NamespaceRecord>& intercepts,
     const std::vector<AppCacheDatabase::NamespaceRecord>& fallbacks,
     const std::vector<AppCacheDatabase::OnlineWhiteListRecord>& whitelists) {
  DCHECK_EQ(cache_id_, cache_record.cache_id);
   online_whitelist_all_ = cache_record.online_wildcard;
   update_time_ = cache_record.update_time;
 
   for (size_t i = 0; i < entries.size(); ++i) {
     const AppCacheDatabase::EntryRecord& entry = entries.at(i);
     AddEntry(entry.url, AppCacheEntry(entry.flags, entry.response_id,
                                      entry.response_size, entry.padding_size));
   }
  DCHECK_EQ(cache_size_, cache_record.cache_size);
  DCHECK_EQ(padding_size_, cache_record.padding_size);
 
   for (size_t i = 0; i < intercepts.size(); ++i)
     intercept_namespaces_.push_back(intercepts.at(i).namespace_);

  for (size_t i = 0; i < fallbacks.size(); ++i)
    fallback_namespaces_.push_back(fallbacks.at(i).namespace_);

  std::sort(intercept_namespaces_.begin(), intercept_namespaces_.end(),
            SortNamespacesByLength);
  std::sort(fallback_namespaces_.begin(), fallback_namespaces_.end(),
            SortNamespacesByLength);

  for (size_t i = 0; i < whitelists.size(); ++i) {
    const AppCacheDatabase::OnlineWhiteListRecord& record = whitelists.at(i);
    online_whitelist_namespaces_.push_back(
        AppCacheNamespace(APPCACHE_NETWORK_NAMESPACE,
                  record.namespace_url,
                  GURL(),
                  record.is_pattern));
  }
}

void AppCache::InitializeWithDatabaseRecords(
    const AppCacheDatabase::CacheRecord& cache_record,
    const std::vector<AppCacheDatabase::EntryRecord>& entries,
     const std::vector<AppCacheDatabase::NamespaceRecord>& intercepts,
     const std::vector<AppCacheDatabase::NamespaceRecord>& fallbacks,
     const std::vector<AppCacheDatabase::OnlineWhiteListRecord>& whitelists) {
  DCHECK(cache_id_ == cache_record.cache_id);
   online_whitelist_all_ = cache_record.online_wildcard;
   update_time_ = cache_record.update_time;
 
   for (size_t i = 0; i < entries.size(); ++i) {
     const AppCacheDatabase::EntryRecord& entry = entries.at(i);
     AddEntry(entry.url, AppCacheEntry(entry.flags, entry.response_id,
                                      entry.response_size));
   }
  DCHECK(cache_size_ == cache_record.cache_size);
 
   for (size_t i = 0; i < intercepts.size(); ++i)
     intercept_namespaces_.push_back(intercepts.at(i).namespace_);

  for (size_t i = 0; i < fallbacks.size(); ++i)
    fallback_namespaces_.push_back(fallbacks.at(i).namespace_);

  std::sort(intercept_namespaces_.begin(), intercept_namespaces_.end(),
            SortNamespacesByLength);
  std::sort(fallback_namespaces_.begin(), fallback_namespaces_.end(),
            SortNamespacesByLength);

  for (size_t i = 0; i < whitelists.size(); ++i) {
    const AppCacheDatabase::OnlineWhiteListRecord& record = whitelists.at(i);
    online_whitelist_namespaces_.push_back(
        AppCacheNamespace(APPCACHE_NETWORK_NAMESPACE,
                  record.namespace_url,
                  GURL(),
                  record.is_pattern));
  }
}
