This CL updates how dangerous downloads are shown on the chrome://downloads page.

(1) It adds the appropriate warning icon to the download info block, for all types of dangerous files.

(2) For known malware: it changes the options to be links that say "Restore malicious file" and "Remove from list".

BUG=305387
TEST=
1. Download a malicious file (e.g., http://download.safebrowsingtest.com/download/test)
2. chrome://downloads should show "Restore malicious file" and "Remove from list" actions next to download, and there should be a red image next to it.
3. Download a dangerous file like a SWF
4. chrome://downloads should show "Keep" and "Discard" buttons & a yellow icon next to the download.

R=asanka@chromium.org, jhawkins@chromium.org

Review URL: https://codereview.chromium.org/26263005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@229483 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 229483