[Mac] Fix DCHECK() on page actions in preview.

chrome/browser/cocoa/autocomplete_text_field_cell.mm

 // Copyright (c) 2010 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/cocoa/autocomplete_text_field_cell.h"
 
 #include "app/resource_bundle.h"
 #include "base/logging.h"
 #include "gfx/font.h"
 
@@ skipping 40 matching lines @@
 CGFloat WidthForHint(NSAttributedString* hintString) {
   return kHintXOffset + ceil([hintString size].width);
 }
 CGFloat WidthForKeyword(NSAttributedString* keywordString) {
   return kKeywordXOffset + ceil([keywordString size].width) +
       2 * kKeywordTokenInset;
 }
 
 // Convenience to draw |image| in the |rect| portion of |view|.
 void DrawImageInRect(NSImage* image, NSView* view, const NSRect& rect) {
-  DCHECK(NSEqualSizes([image size], rect.size));
+  // If there is an image, make sure we calculated the target size
+  // correctly.
+  DCHECK(!image || NSEqualSizes([image size], rect.size));
   [image setFlipped:[view isFlipped]];
   [image drawInRect:rect
            fromRect:NSZeroRect  // Entire image
           operation:NSCompositeSourceOver
            fraction:1.0];
 }
 
 }  // namespace
 
 @implementation AutocompleteTextFieldIcon
@@ skipping 448 matching lines @@
       icon = [self iconForEvent:theEvent inRect:cellFrame ofView:controlView];
   if (icon) {
     [icon view]->OnMousePressed([icon rect]);
     return YES;
   }
 
   return NO;
 }
 
 @end