Backing out r20493 (http://codereview.chromium.org/149492), as it inadvertent...

chrome/browser/autocomplete/autocomplete_edit_view_mac.mm

 // 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.
 
 #include "chrome/browser/autocomplete/autocomplete_edit_view_mac.h"
 
 #include "base/sys_string_conversions.h"
 #include "chrome/browser/autocomplete/autocomplete_edit.h"
 #include "chrome/browser/autocomplete/autocomplete_popup_model.h"
 #include "chrome/browser/autocomplete/autocomplete_popup_view_mac.h"
@@ skipping 531 matching lines @@
 void AutocompleteEditViewMac::OnDidResignKey() {
   ClosePopup();
 }
 
 void AutocompleteEditViewMac::AcceptInput(
     WindowOpenDisposition disposition, bool for_drop) {
   model_->AcceptInput(disposition, for_drop);
 }
 
 void AutocompleteEditViewMac::FocusLocation() {
-  [[field_ window] makeFirstResponder:field_];
-  DCHECK_EQ([field_ currentEditor], [[field_ window] firstResponder]);
+  // -makeFirstResponder: will select the entire field_.  If we're
+  // already firstResponder, it's likely that we want to retain the
+  // current selection.
+  if (![field_ currentEditor]) {
+    [[field_ window] makeFirstResponder:field_];
+    DCHECK_EQ([field_ currentEditor], [[field_ window] firstResponder]);
+  }
 }
 
 @implementation AutocompleteFieldDelegate
 
 - initWithEditView:(AutocompleteEditViewMac*)view {
   self = [super init];
   if (self) {
     edit_view_ = view;
   }
   return self;
@@ skipping 58 matching lines @@
   // TODO(shess): Figure out where the selection belongs.  On GTK,
   // it's set to the start of the text.
 }
 
 // Signal that we've lost focus when the window resigns key.
 - (void)windowDidResignKey:(NSNotification*)notification {
   edit_view_->OnDidResignKey();
 }
 
 @end