[Mac] Handle backspacing out of keyword search.

chrome/browser/autocomplete/autocomplete_edit_view_mac.h

 // Copyright (c) 2009 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_AUTOCOMPLETE_AUTOCOMPLETE_EDIT_VIEW_MAC_H_
 #define CHROME_BROWSER_AUTOCOMPLETE_AUTOCOMPLETE_EDIT_VIEW_MAC_H_
 
 #import <Cocoa/Cocoa.h>
 
 #include "base/basictypes.h"
@@ skipping 98 matching lines @@
   // visual state (such as closing the popup).
   void OnDidResignKey();
 
   // Called when the user attempts to paste into |field_|.
   void OnPaste();
 
   // Checks if a keyword search is possible and forwards to |model_|
   // if so.  Returns true if the tab should be eaten.
   bool OnTabPressed();
 
+  // Called when the user hits backspace in |field_|.  Checks whether
+  // keyword search is being terminated.  Returns true if the
+  // backspace should be intercepted (not forwarded on to the standard
+  // machinery).
+  bool OnBackspacePressed();
+
   void AcceptInput(WindowOpenDisposition disposition, bool for_drop);
 
   // Helper for LocationBarViewMac.  Selects all in |field_|.
   void FocusLocation();
 
   // Helper to get appropriate contents from |clipboard|.  Returns
   // empty string if no appropriate data is found on |clipboard|.
   static std::wstring GetClipboardText(Clipboard* clipboard);
 
  private:
@@ skipping 45 matching lines @@
 
   // Tracking state before and after a possible change for reporting
   // to model_.
   NSRange selection_before_change_;
   std::wstring text_before_change_;
 
   DISALLOW_COPY_AND_ASSIGN(AutocompleteEditViewMac);
 };
 
 #endif  // CHROME_BROWSER_AUTOCOMPLETE_AUTOCOMPLETE_EDIT_VIEW_MAC_H_