Disk cache: Re-enable DiskCacheEntryTest.CancelSparseIO
Disk cache: Re-enable DiskCacheEntryTest.CancelSparseIO

I still don't know why it failed, but the only difference
?\127that I could see in this test between xp and vista is that
xp accepts a lot of small IOs before returning pending, so
this change results in similar behavior in both platforms
and a faster run on xp.

BUG=23862
TEST=none


Review URL: http://codereview.chromium.org/273024

git-svn-id: dd90618784b6a4b323ea0c23a071cb1c9e6f2ac7@28921 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser