Collapse fileapi, webkit_blob, webkit_database, quota, and webkit_common namespaces into single storage namespace

As discussed here:
https://groups.google.com/a/chromium.org/forum/#!topic/storage-dev/aQall8GOrS4

BUG=338338
TBR=cevans
NOTRY=true

Review URL: https://codereview.chromium.org/492873002

Cr-Commit-Position: refs/heads/master@{#291485}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@291485 0039d316-1c4b-4281-b951-d872f2087c98
711 files changed