Code:   void StoreExistingGroup() {
    PushNextTask(
        base::BindOnce(&AppCacheStorageImplTest::Verify_StoreExistingGroup,
                       base::Unretained(this)));

     MakeCacheAndGroup(kManifestUrl, 1, 1, true);
    EXPECT_EQ(kDefaultEntrySize, storage()->usage_map_[kOrigin]);
 
     cache2_ = new AppCache(storage(), 2);
    cache2_->AddEntry(kEntryUrl, AppCacheEntry(AppCacheEntry::MASTER, 1,
                                               kDefaultEntrySize + 100));
 
     storage()->StoreGroupAndNewestCache(group_.get(), cache2_.get(),
                                        delegate());
    EXPECT_FALSE(delegate()->stored_group_success_);
  }

Commit Message: 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}
CWE ID: CWE-200
  void StoreExistingGroup() {
    PushNextTask(
        base::BindOnce(&AppCacheStorageImplTest::Verify_StoreExistingGroup,
                       base::Unretained(this)));

     MakeCacheAndGroup(kManifestUrl, 1, 1, true);
    EXPECT_EQ(kDefaultEntrySize + kDefaultEntryPadding,
              storage()->usage_map_[kOrigin]);
 
     cache2_ = new AppCache(storage(), 2);
    cache2_->AddEntry(kEntryUrl, AppCacheEntry(AppCacheEntry::EXPLICIT, 1,
                                               kDefaultEntrySize + 100,
                                               kDefaultEntryPadding + 1000));
 
     storage()->StoreGroupAndNewestCache(group_.get(), cache2_.get(),
                                        delegate());
    EXPECT_FALSE(delegate()->stored_group_success_);
  }
