[Textfield] Consider select all status for select all context menu

ui/views/controls/textfield/textfield.cc

 // 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 "ui/views/controls/textfield/textfield.h"
 
 #include <string>
 #include <utility>
 
 #include "base/memory/ptr_util.h"
@@ skipping 1528 matching lines @@
       return editable && model_->CanRedo();
     case ui::TextEditCommand::CUT:
       return editable && readable && model_->HasSelection();
     case ui::TextEditCommand::COPY:
       return readable && model_->HasSelection();
     case ui::TextEditCommand::PASTE:
       ui::Clipboard::GetForCurrentThread()->ReadText(
           ui::CLIPBOARD_TYPE_COPY_PASTE, &result);
       return editable && !result.empty();
     case ui::TextEditCommand::SELECT_ALL:
-      return !text().empty();
+      return !text().empty() && GetSelectedRange().length() != text().length();
     case ui::TextEditCommand::TRANSPOSE:
       return editable && !model_->HasSelection() &&
              !model_->HasCompositionText();
     case ui::TextEditCommand::YANK:
       return editable;
     case ui::TextEditCommand::MOVE_DOWN:
     case ui::TextEditCommand::MOVE_DOWN_AND_MODIFY_SELECTION:
     case ui::TextEditCommand::MOVE_PAGE_DOWN:
     case ui::TextEditCommand::MOVE_PAGE_DOWN_AND_MODIFY_SELECTION:
     case ui::TextEditCommand::MOVE_PAGE_UP:
@@ skipping 538 matching lines @@
   cursor_blink_timer_.Stop();
 }
 
 void Textfield::OnCursorBlinkTimerFired() {
   DCHECK(ShouldBlinkCursor());
   cursor_view_.SetVisible(!cursor_view_.visible());
   UpdateCursorViewPosition();
 }
 
 }  // namespace views