Mac version of the download shelf views

The Mac version of the download shelf from the original CL by thakis:
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.


Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=20200

[Paul Godavari, 2009-07-07 22:41:34]

Originally was http://codereview.chromium.org/150216

This new CL includes fixes for your comments in the previous version, with
the exception of leaving the following as TODOs for a follow up CL:
- load icons on the file thread via IconManager
- putting menu tags in the nib

[pink (ping after 24hrs), 2009-07-08 14:24:07]

LGTM with small issues addressed.

http://codereview.chromium.org/149276/diff/1037/55
File chrome/browser/cocoa/download_item_controller.h (right):

http://codereview.chromium.org/149276/diff/1037/55#newcode26
Line 26: // Takes ownership of |download_model|.
update comment with new name

http://codereview.chromium.org/149276/diff/1037/55#newcode30
Line 30: - (void)setStateFromDownload:(BaseDownloadItemModel*)downloadModel;
comment for function in public API. What state does it set?

http://codereview.chromium.org/149276/diff/1037/56
File chrome/browser/cocoa/download_item_controller.mm (right):

http://codereview.chromium.org/149276/diff/1037/56#newcode49
Line 49: [self setStateFromDownload:bridge_->download_model()];
indented too far?

http://codereview.chromium.org/149276/diff/1037/56#newcode70
Line 70: // TODO(paulg): Use IconManager for loading icons on the file thread.
file a bug so we don't forget? or is that overkill because it's already on your
radar?

http://codereview.chromium.org/149276/diff/1037/56#newcode86
Line 86: - (BOOL)validateMenuItem:(NSMenuItem *)item {
function-level comment.

http://codereview.chromium.org/149276/diff/1037/60
File chrome/browser/cocoa/download_shelf_controller.mm (right):

http://codereview.chromium.org/149276/diff/1037/60#newcode175
Line 175: DownloadItemController* controller =
you can just make this a scoped_nsobject rather than doing the autorelease on
the separate line.