continuing from http://http://codereview.chromium.org/10823241

This intentionally doesn't change the ChromeOS behavior at all.  They all still use the default FileSystemContext.

This code also exposes the normal and media URLRequestGetters via the StoragePartition, and cleans up a bit of code that was accessing the URLRequestGetter in odd ways.  Also, it makes Workers correctly use the Media Cache for Media fetches.

TBR=benjhyden,sky,davemoore,piman,mkwst,kalman
BUG=85121

Review URL: https://chromiumcodereview.appspot.com/10909182

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@157284 0039d316-1c4b-4281-b951-d872f2087c98
42 files changed