Disk Cache: Improve handling of dirty entries.

Disk Cache: Improve handling of dirty entries.

* Split the entry sanity checks in two parts: a critical one
and a non-critical one. This allows us to return dirty entries
instead of failing to open them.

* Make sure that we cannot reach an entry through the index
before the actual data reaches the disk (when creating an entry
linked through a parent we were not respecting that).

* When deleting a block from a block file, first clean it
up and then update the map (avoid leaving a dirty free block
if there is a crash)

* Handle the case of errors when opening entries through the
enumerations path.

BUG=73102
TEST=net_unittests
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=103323

[gavinp, 2011-09-29 13:25:34]

LGTM, with the typo fixed.

http://codereview.chromium.org/8065015/diff/1/net/disk_cache/backend_impl.cc
File net/disk_cache/backend_impl.cc (right):

http://codereview.chromium.org/8065015/diff/1/net/disk_cache/backend_impl.cc#...
net/disk_cache/backend_impl.cc:765: // and finally thorugh the lists. If there
is a crash in this process, we may
typo: thorugh -> through

http://codereview.chromium.org/8065015/diff/1/net/disk_cache/rankings.cc
File net/disk_cache/rankings.cc (right):

http://codereview.chromium.org/8065015/diff/1/net/disk_cache/rankings.cc#newc...
net/disk_cache/rankings.cc:819: bool Rankings::IsHead(CacheAddr addr, List*
list) const {
Good catch.