Reviewed by Adam Barth.

        Use a File object to store the downloaded file reference rather than
        just the path. This keeps the file and permissions in scope (using the
        already-existing blob system) so the browser won't delete the file
        when the load is complete. Instead, the file will be cleaned up when
        the request objects are deleted.
        https://bugs.webkit.org/show_bug.cgi?id=60281

        * platform/network/chromium/ResourceResponse.cpp:
        (WebCore::ResourceResponse::doPlatformCopyData):
        (WebCore::ResourceResponse::doPlatformAdopt):
        * platform/network/chromium/ResourceResponse.h:
        (WebCore::ResourceResponse::downloadedFile):
        (WebCore::ResourceResponse::setDownloadedFile):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@86164 268f45cc-cd09-0410-ab3c-d52691b4dbfc