Implement {Start,Stop}CapturingKeyStrokes for Instant.

chrome/browser/ui/cocoa/omnibox/omnibox_view_mac.mm

 // 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.
 
 #include "chrome/browser/ui/cocoa/omnibox/omnibox_view_mac.h"
 
 #include <Carbon/Carbon.h>  // kVK_Return
 
 #include "base/string_util.h"
 #include "base/sys_string_conversions.h"
@@ skipping 344 matching lines @@
 
 void OmniboxViewMac::CloseOmniboxPopup() {
   // Call both base class methods.
   ClosePopup();
   OmniboxView::CloseOmniboxPopup();
 }
 
 void OmniboxViewMac::SetFocus() {
 }
 
+void OmniboxViewMac::SetInvisibleFocus() {
+  // TODO(mathp): implement for Mac.
+  NOTIMPLEMENTED();
+}
+
 void OmniboxViewMac::SetText(const string16& display_text) {
   // If we are setting the text directly, there cannot be any suggest text.
   suggest_text_length_ = 0;
   SetTextInternal(display_text);
 }
 
 void OmniboxViewMac::SetTextInternal(const string16& display_text) {
   NSString* ss = base::SysUTF16ToNSString(display_text);
   NSMutableAttributedString* as =
       [[[NSMutableAttributedString alloc] initWithString:ss] autorelease];
@@ skipping 631 matching lines @@
 NSUInteger OmniboxViewMac::GetTextLength() const {
   return ([field_ currentEditor] ?
           [[[field_ currentEditor] string] length] :
           [[field_ stringValue] length]) - suggest_text_length_;
 }
 
 bool OmniboxViewMac::IsCaretAtEnd() const {
   const NSRange selection = GetSelectedRange();
   return selection.length == 0 && selection.location == GetTextLength();
 }