GitLab

Move code from StoragePartitionHttpCacheRemover to CacheCountingHelper. Improve tests by adding a CacheTestUtil class for common functionality of cache counting and cache deletion tests.

BUG=671196
TBR=achuith@chromium.org

Review-Url: https://codereview.chromium.org/2556363003
Cr-Commit-Position: refs/heads/master@{#441399}