Have SearchProvider look up the omnibox start margin directly.

chrome/browser/ui/cocoa/location_bar/location_bar_view_mac.mm

Index: chrome/browser/ui/cocoa/location_bar/location_bar_view_mac.mm
diff --git a/chrome/browser/ui/cocoa/location_bar/location_bar_view_mac.mm b/chrome/browser/ui/cocoa/location_bar/location_bar_view_mac.mm
index ec510a6f0b26cd29636480b178745f55143ed193..b3dde0c522d118194ecb51fd7781a09c132e428e 100644
--- a/chrome/browser/ui/cocoa/location_bar/location_bar_view_mac.mm
+++ b/chrome/browser/ui/cocoa/location_bar/location_bar_view_mac.mm
@@ -357,10 +357,6 @@ WebContents* LocationBarViewMac::GetWebContents() const {
   return browser_->tab_strip_model()->GetActiveWebContents();
 }
 
-gfx::Rect LocationBarViewMac::GetOmniboxBounds() const {
-  return gfx::Rect(NSRectToCGRect([field_ frame]));
-}
-
 PageActionDecoration* LocationBarViewMac::GetPageActionDecoration(
     ExtensionAction* page_action) {
   DCHECK(page_action);