[Mac] Handle backspacing out of keyword search.

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 <Carbon/Carbon.h>  // kVK_Return
 #include "app/gfx/font.h"
 #include "app/resource_bundle.h"
 #include "base/clipboard.h"
@@ skipping 612 matching lines @@
 }
 
 bool AutocompleteEditViewMac::OnTabPressed() {
   if (model_->is_keyword_hint() && !model_->keyword().empty()) {
     model_->AcceptKeyword();
     return true;
   }
   return false;
 }
 
+bool AutocompleteEditViewMac::OnBackspacePressed() {
+  // Don't intercept if not in keyword search mode.
+  if (model_->is_keyword_hint() || model_->keyword().empty()) {
+    return false;
+  }
+
+  // Don't intercept if there is a selection, or the cursor isn't at
+  // the leftmost position.
+  const NSRange selection = GetSelectedRange();
+  if (selection.length > 0 || selection.location > 0) {
+    return false;
+  }
+
+  // We're showing a keyword and the user pressed backspace at the
+  // beginning of the text.  Delete the selected keyword.
+  model_->ClearKeyword(GetText());
+  return true;
+}
+
 bool AutocompleteEditViewMac::IsPopupOpen() const {
   return popup_view_->IsOpen();
 }
 
 void AutocompleteEditViewMac::OnControlKeyChanged(bool pressed) {
   model_->OnControlKeyChanged(pressed);
 }
 
 void AutocompleteEditViewMac::AcceptInput(
     WindowOpenDisposition disposition, bool for_drop) {
@@ skipping 107 matching lines @@
   // received notification when the Control key was depressed, but it
   // is safe to tell it twice.
   if (cmd == @selector(insertLineBreak:)) {
     edit_view_->OnControlKeyChanged(true);
     WindowOpenDisposition disposition =
         event_utils::WindowOpenDispositionFromNSEvent([NSApp currentEvent]);
     edit_view_->AcceptInput(disposition, false);
     return YES;
   }
 
+  if (cmd == @selector(deleteBackward:)) {
+    if (edit_view_->OnBackspacePressed()) {
+      return YES;
+    }
+  }
+
   // Capture the state before the operation changes the content.
   // TODO(shess): Determine if this is always redundent WRT the call
   // in -controlTextDidChange:.
   edit_view_->OnBeforePossibleChange();
   return NO;
 }
 
 - (void)controlTextDidBeginEditing:(NSNotification*)aNotification {
   edit_view_->OnWillBeginEditing();
 }
@@ skipping 36 matching lines @@
 // prepended and ".com" appended.  This calls down to
 // AutocompleteEditModel::OnControlKeyChanged() so that it can change
 // the popup to reflect this.  See autocomplete_edit.cc
 // OnControlKeyChanged() and OnAfterPossibleChange().
 - (void)control:(NSControl*)control flagsChanged:(NSEvent*)theEvent {
   BOOL controlFlag = ([theEvent modifierFlags]&NSControlKeyMask) != 0;
   edit_view_->OnControlKeyChanged(controlFlag);
 }
 
 @end