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

chrome/browser/cocoa/autocomplete_text_field_cell.mm

Index: chrome/browser/cocoa/autocomplete_text_field_cell.mm
diff --git a/chrome/browser/cocoa/autocomplete_text_field_cell.mm b/chrome/browser/cocoa/autocomplete_text_field_cell.mm
index c8f2122afbcbed9a6028b9dc207bc17eae77e306..0543bf6e3bebaf8e183d2e36bbbb78514d5a07c6 100644
--- a/chrome/browser/cocoa/autocomplete_text_field_cell.mm
+++ b/chrome/browser/cocoa/autocomplete_text_field_cell.mm
@@ -58,7 +58,9 @@ CGFloat WidthForKeyword(NSAttributedString* keywordString) {
 
 // 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