Total guess fix for the bug....

chrome/browser/autocomplete/autocomplete_popup_view_mac.mm

 // Copyright (c) 2009 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.
 
 #include "chrome/browser/autocomplete/autocomplete_popup_view_mac.h"
 
 #include "app/gfx/text_elider.h"
 #include "app/resource_bundle.h"
 #include "base/sys_string_conversions.h"
 #include "base/gfx/rect.h"
@@ skipping 26 matching lines @@
 // autocomplete_popup_contents_view.cc, kGlassPopupTransparency).
 const CGFloat kPopupAlpha = 240.0 / 255.0;
 
 // How much space to leave for the left and right margins.
 const CGFloat kLeftRightMargin = 8.0;
 
 // How far to offset the text column from the left.
 const CGFloat kTextXOffset = 33.0;
 
 // Animation duration when animating the popup window smaller.
-const float kShrinkAnimationDuration = 0.1;
+const CGFloat kShrinkAnimationDuration = 0.1;
 
 // Maximum fraction of the popup width that can be used to display match
 // contents.
 const float kMaxContentsFraction = 0.7;
 
 // NSEvent -buttonNumber for middle mouse button.
 const static NSInteger kMiddleButtonNumber(2);
 
 // Background colors for different states of the popup elements.
 NSColor* BackgroundColor() {
@@ skipping 300 matching lines @@
     AutocompleteMatrix* matrix =
         [[[AutocompleteMatrix alloc] initWithFrame:NSZeroRect] autorelease];
     [matrix setTarget:matrix_target_];
     [matrix setAction:@selector(select:)];
     [matrix setMiddleClickAction:@selector(middleSelect:)];
     [popup_ setContentView:matrix];
   }
 }
 
 void AutocompletePopupViewMac::UpdatePopupAppearance() {
+  DCHECK([NSThread isMainThread]);
   const AutocompleteResult& result = model_->result();
   if (result.empty()) {
     [[popup_ parentWindow] removeChildWindow:popup_];
     [popup_ orderOut:nil];
 
     // Break references to matrix_target_ before releasing popup_.
     NSMatrix* matrix = [popup_ contentView];
     [matrix setTarget:nil];
 
     popup_.reset(nil);
@@ skipping 345 matching lines @@
   DCHECK(popup_view_);
   popup_view_->OnClick();
 }
 
 - (void)middleSelect:(id)sender {
   DCHECK(popup_view_);
   popup_view_->OnMiddleClick();
 }
 
 @end