Adding (empty) placeholder button to 'Other bookmarks' folder is unnecessary.

chrome/browser/ui/cocoa/bookmarks/bookmark_bar_folder_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/bookmarks/bookmark_bar_folder_controller.h"
 
 #include "base/mac/bundle_locations.h"
 #include "base/mac/mac_util.h"
 #include "base/strings/sys_string_conversions.h"
 #import "chrome/browser/bookmarks/bookmark_model_factory.h"
@@ skipping 744 matching lines @@
     if (metrics.canScrollUp || metrics.canScrollDown)
       [self addOrUpdateScrollTracking];
     else
       [self removeScrollTracking];
   }
 }
 
 - (void)adjustWindowForButtonCount:(NSUInteger)buttonCount {
   NSRect folderFrame = [folderView_ frame];
   CGFloat newMenuHeight =
-      (CGFloat)[self menuHeightForButtonCount:[buttons_ count]];
+      (CGFloat)[self menuHeightForButtonCount:buttonCount];
   CGFloat deltaMenuHeight = newMenuHeight - NSHeight(folderFrame);
   // If the height has changed then also change the origin, and adjust the
   // scroll (if scrolling).
   if ([self canScrollUp]) {
     NSPoint scrollPoint = [scrollView_ documentVisibleRect].origin;
     scrollPoint.y += deltaMenuHeight;
     [[scrollView_ documentView] scrollPoint:scrollPoint];
   }
   folderFrame.size.height += deltaMenuHeight;
   [folderView_ setFrameSize:folderFrame.size];
@@ skipping 1153 matching lines @@
   // Search for and adjust submenus, if necessary.
   NSInteger buttonCount = [buttons_ count];
   if (buttonCount) {
     BookmarkButton* subButton = [folderController_ parentButton];
     for (NSButton* aButton in buttons_.get()) {
       // If this button is showing its menu then we need to move the menu, too.
       if (aButton == subButton)
         [folderController_
             offsetFolderMenuWindow:NSMakeSize(0.0, chrome::kBookmarkBarHeight)];
     }
-  } else {
+  } else if (parentButton_ != [barController_ otherBookmarksButton]) {
     // If all nodes have been removed from this folder then add in the
-    // 'empty' placeholder button.
+    // 'empty' placeholder button except for "Other bookmarks" folder
+    // as we are going to hide it.
     NSRect buttonFrame =
         GetFirstButtonFrameForHeight([self menuHeightForButtonCount:1]);
     BookmarkButton* button = [self makeButtonForNode:nil
                                                frame:buttonFrame];
     [buttons_ addObject:button];
     [folderView_ addSubview:button];
     buttonCount = 1;
   }
 
-  [self adjustWindowForButtonCount:buttonCount];
+  // buttonCount will be 0 if "Other bookmarks" folder is empty, so close
+  // the folder before hiding it.
+  if (buttonCount == 0)
+    [barController_ closeBookmarkFolder:nil];
+  else if (buttonCount > 0)
+    [self adjustWindowForButtonCount:buttonCount];
 
   if (animate && !ignoreAnimations_)
     NSShowAnimationEffect(NSAnimationEffectDisappearingItemDefault, poofPoint,
                           NSZeroSize, nil, nil, nil);
 }
 
 - (id<BookmarkButtonControllerProtocol>)controllerForNode:
     (const BookmarkNode*)node {
   // See if we are holding this node, otherwise see if it is in our
   // hierarchy of visible folder menus.
@@ skipping 30 matching lines @@
 
 - (void)setIgnoreAnimations:(BOOL)ignore {
   ignoreAnimations_ = ignore;
 }
 
 - (BookmarkButton*)buttonThatMouseIsIn {
   return buttonThatMouseIsIn_;
 }
 
 @end  // BookmarkBarFolderController