Clear media cache when clearing browsing data
Clear media cache when clearing browsing data

BUG=24765
BUG=24813
TEST=run Chromium with --enable-byte-range-support, watch a movie, clear
     browsing data, Media Cache folder shouldn't have the cache files.

Clear media cache when clearing browsing data. What's missing in this patch
is that disk_cache in HttpCache is lazily initialized, so it has to be used
at least once before we can clear it.

Review URL: http://codereview.chromium.org/275013

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@28992 0039d316-1c4b-4281-b951-d872f2087c98

ropik/chromium,adobe/chromium,ropik/chromium,ropik/chromium,yitian134/chromium,Crystalnix/house-of-life-chromium,yitian134/chromium,Crystalnix/house-of-life-chromium,ropik/chromium,gavinp/chromium,adobe/chromium,gavinp/chromium,adobe/chromium,adobe/chromium,ropik/chromium,yitian134/chromium,yitian134/chromium,yitian134/chromium,Crystalnix/house-of-life-chromium,ropik/chromium,Crystalnix/house-of-life-chromium,gavinp/chromium,yitian134/chromium,gavinp/chromium,Crystalnix/house-of-life-chromium,ropik/chromium,gavinp/chromium,adobe/chromium,gavinp/chromium,gavinp/chromium,Crystalnix/house-of-life-chromium,gavinp/chromium,adobe/chromium,yitian134/chromium,adobe/chromium,Crystalnix/house-of-life-chromium,gavinp/chromium,Crystalnix/house-of-life-chromium,yitian134/chromium,Crystalnix/house-of-life-chromium,gavinp/chromium,ropik/chromium,yitian134/chromium,yitian134/chromium,Crystalnix/house-of-life-chromium,Crystalnix/house-of-life-chromium,adobe/chromium,adobe/chromium,ropik/chromium,adobe/chromium,adobe/chromium