mac: Move the bookmark bar overflow chevron from pdf to png

chrome/browser/ui/cocoa/bookmarks/bookmark_button_cell.mm

Index: chrome/browser/ui/cocoa/bookmarks/bookmark_button_cell.mm
diff --git a/chrome/browser/ui/cocoa/bookmarks/bookmark_button_cell.mm b/chrome/browser/ui/cocoa/bookmarks/bookmark_button_cell.mm
index 25c7d8fdbafbca03e5856fc3f1b202ecbb3d5e77..5c636fc93905b6e95dfd77fe2bfab7f0cc59c12a 100644
--- a/chrome/browser/ui/cocoa/bookmarks/bookmark_button_cell.mm
+++ b/chrome/browser/ui/cocoa/bookmarks/bookmark_button_cell.mm
@@ -91,6 +91,10 @@ using content::UserMetricsAction;
   // try to match Windows for a bit to see what happens.
   [self setLineBreakMode:NSLineBreakByTruncatingTail];
 
+  // The overflow button chevron bitmap is not 16 units high, so it'd be scaled
+  // at paint time without this.
+  [self setImageScaling:NSImageScaleNone];
+
   // Theming doesn't work for bookmark buttons yet (cell text is chucked).
   [super setShouldTheme:NO];
 }