[Mac] Re-layout download shelf when danger state of item changes.

chrome/browser/ui/cocoa/download/download_item_controller.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import <Cocoa/Cocoa.h>
 
 #include "base/memory/scoped_ptr.h"
 #include "base/time/time.h"
 
 @class ChromeUILocalizer;
@@ skipping 16 matching lines @@
 
 namespace gfx {
 class FontList;
 }
 
 namespace ui {
 class MenuModel;
 }
 
 // A controller class that manages one download item.
-
+//
+// The view hierarchy is as follows:
+//
+// DownloadItemController
+//  |
+//  |  A container that is showing one of its child views (progressView_ or
+//  |  dangerousDownloadView_) depending on whether the download is safe or not.
+//  |
+//  +-- progressView_ (instance of DownloadItemButton)
+//  |   |
+//  |   +-- cell_ (instance of DownloadItemCell)
+//  |
+//  +-- dangerousDownloadView_
+//      |
+//      |  Contains the dangerous download warning. Dependong on whether the
+//      |  download is dangerous (e.g. dangerous due to type of file), or
+//      |  malicious (e.g. downloaded from a known malware site) only one of
+//      |  dangerousButtonTweaker_ or maliciousButtonTweaker_ will be visible at
+//      |  one time.
+//      |
+//      +-- dangerousDownloadLabel_
+//      |
+//      +-- image_
+//      |
+//      +-- dangerousButtonTweaker_
+//      |
+//      |  Contains the 'Discard'/'Save' buttons for a dangerous download. This
+//      |  is a GTMWidthBasedTweaker that adjusts the width based on the text of
+//      |  buttons.
+//      |
+//      +-- maliciousButtonTweaker_
+//
+//         Contains the 'Discard' button and the drop down context menu button.
+//         This is a GTMWidthBasedTweaker that adjusts the width based on the
+//         text of the 'Discard' button.
+//
 @interface DownloadItemController : NSViewController {
  @private
   IBOutlet DownloadItemButton* progressView_;
   IBOutlet DownloadItemCell* cell_;
 
   // This is shown instead of progressView_ for dangerous downloads.
   IBOutlet NSView* dangerousDownloadView_;
   IBOutlet NSTextField* dangerousDownloadLabel_;
   IBOutlet NSButton* dangerousDownloadConfirmButton_;
 
@@ skipping 72 matching lines @@
 - (void)updateToolTip;
 
 // Handling of dangerous downloads
 - (void)clearDangerousMode;
 - (BOOL)isDangerousMode;
 - (IBAction)saveDownload:(id)sender;
 - (IBAction)discardDownload:(id)sender;
 - (IBAction)dismissMaliciousDownload:(id)sender;
 - (IBAction)showContextMenu:(id)sender;
 @end