Have SearchProvider look up the omnibox start margin directly.

chrome/browser/ui/views/location_bar/location_bar_view.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_VIEWS_LOCATION_BAR_LOCATION_BAR_VIEW_H_
 #define CHROME_BROWSER_UI_VIEWS_LOCATION_BAR_LOCATION_BAR_VIEW_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 243 matching lines @@
                                     const GURL& alternate_nav_url) OVERRIDE;
   virtual void OnChanged() OVERRIDE;
   virtual void OnSelectionBoundsChanged() OVERRIDE;
   virtual void OnInputInProgress(bool in_progress) OVERRIDE;
   virtual void OnKillFocus() OVERRIDE;
   virtual void OnSetFocus() OVERRIDE;
   virtual gfx::Image GetFavicon() const OVERRIDE;
   virtual string16 GetTitle() const OVERRIDE;
   virtual InstantController* GetInstant() OVERRIDE;
   virtual content::WebContents* GetWebContents() const OVERRIDE;
-  virtual gfx::Rect GetOmniboxBounds() const OVERRIDE;
 
   // views::View:
   virtual const char* GetClassName() const OVERRIDE;
   virtual bool SkipDefaultKeyEventProcessing(
       const ui::KeyEvent& event) OVERRIDE;
   virtual void GetAccessibleState(ui::AccessibleViewState* state) OVERRIDE;
   virtual bool HasFocus() const OVERRIDE;
   virtual void OnBoundsChanged(const gfx::Rect& previous_bounds) OVERRIDE;
 
   // views::ButtonListener:
@@ skipping 246 matching lines @@
   // in the right location.
   int animation_offset_;
 
   // Used to register for notifications received by NotificationObserver.
   content::NotificationRegistrar registrar_;
 
   DISALLOW_COPY_AND_ASSIGN(LocationBarView);
 };
 
 #endif  // CHROME_BROWSER_UI_VIEWS_LOCATION_BAR_LOCATION_BAR_VIEW_H_