Have SearchProvider look up the omnibox start margin directly.

chrome/browser/ui/omnibox/omnibox_edit_controller.h

 // Copyright (c) 2012 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.
 
 #ifndef CHROME_BROWSER_UI_OMNIBOX_OMNIBOX_EDIT_CONTROLLER_H_
 #define CHROME_BROWSER_UI_OMNIBOX_OMNIBOX_EDIT_CONTROLLER_H_
 
 #include "base/strings/string16.h"
 #include "content/public/common/page_transition_types.h"
 #include "ui/base/window_open_disposition.h"
 
 class GURL;
 class InstantController;
 
 namespace content {
 class WebContents;
 }
 
 namespace gfx {
 class Image;
-class Rect;
 }
 
 // I am in hack-and-slash mode right now.
 // http://code.google.com/p/chromium/issues/detail?id=6772
 
 // Embedders of an AutocompleteEdit widget must implement this class.
 class OmniboxEditController {
  public:
   // When the user presses enter or selects a line with the mouse, this
   // function will get called synchronously with the url to open and
@@ skipping 31 matching lines @@
 
   // Returns the title of the current page.
   virtual string16 GetTitle() const = 0;
 
   // Returns the InstantController, or NULL if instant is not enabled.
   virtual InstantController* GetInstant() = 0;
 
   // Returns the WebContents of the currently active tab.
   virtual content::WebContents* GetWebContents() const = 0;
 
-  // Returns the bounds for the omnibox.
-  virtual gfx::Rect GetOmniboxBounds() const = 0;
-
  protected:
   virtual ~OmniboxEditController() {}
 };
 
 #endif  // CHROME_BROWSER_UI_OMNIBOX_OMNIBOX_EDIT_CONTROLLER_H_