Mac: Remove download shelf from AX hierarchy when not visible

chrome/browser/ui/cocoa/download/download_shelf_controller.mm

 // 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 "chrome/browser/ui/cocoa/download/download_shelf_controller.h"
 
 #include "base/mac/bundle_locations.h"
 #include "base/mac/mac_util.h"
 #include "base/strings/sys_string_conversions.h"
 #include "chrome/browser/download/download_stats.h"
@@ skipping 234 matching lines @@
     RecordDownloadShelfClose(
         [downloadItemControllers_ count], numInProgress, !isUserAction);
   }
 
   // Animate the shelf out, but not in.
   // TODO(rohitrao): We do not animate on the way in because Cocoa is already
   // doing a lot of work to set up the download arrow animation.  I've chosen to
   // do no animation over janky animation.  Find a way to make animating in
   // smoother.
   AnimatableView* view = [self animatableView];
-  if (show)
+  if (show) {
     [view setHeight:maxShelfHeight_];
-  else
+    [view setHidden:NO];
+  } else {
     [view animateToNewHeight:0 duration:kDownloadShelfCloseDuration];
+  }
 
   barIsVisible_ = show;
   [self updateCloseButton];
 }
 
 - (DownloadShelf*)bridge {
   return bridge_.get();
 }
 
 - (BOOL)isVisible {
   return barIsVisible_;
 }
 
 - (void)animationDidEnd:(NSAnimation*)animation {
-  if (![self isVisible])
+  if (![self isVisible]) {
     [self closed];
+    [[self view] setHidden:YES];  // So that it doesn't appear in AX hierarchy.
+  }
 }
 
 - (float)height {
   return maxShelfHeight_;
 }
 
 // If |skipFirst| is true, the frame of the leftmost item is not set.
 - (void)layoutItems:(BOOL)skipFirst {
   CGFloat currentX = 0;
   for (DownloadItemController* itemController
@@ skipping 216 matching lines @@
   }
 
   // Set the tracking off to create a new tracking area for the control.
   // When changing the bounds/frame on a HoverButton, the tracking isn't updated
   // correctly, it needs to be turned off and back on.
   [hoverCloseButton_ setTrackingEnabled:NO];
   [hoverCloseButton_ setFrame:bounds];
   [hoverCloseButton_ setTrackingEnabled:YES];
 }
 @end