GitLab

http://codereview.chromium.org/150216

Original description:
Move download item to its own view and a xib, paving the way for a custom
download item view. I didn't change the look of the download items yet. The
context menu is now in the download item xib as well.

BUG=14659,15098,14660
TEST=Download something. Everything should look like before (except for the
     smaller icon), but the context menu items should be disabled/enabled and
     checked/unchecked correctly.

Review URL: http://codereview.chromium.org/149276

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@20200 0039d316-1c4b-4281-b951-d872f2087c98