Adds write-from-local-file support for the ImageWriterPrivate API.

BUG=313515

Review URL: https://codereview.chromium.org/53953002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@238802 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 238802