Conservative update button/label/textfield content

ui/views/controls/button/text_button.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/button/text_button.h"
 
 #include <algorithm>
 
 #include "base/logging.h"
 #include "grit/ui_resources.h"
@@ skipping 273 matching lines @@
     return;
   is_default_ = is_default;
   if (is_default_)
     AddAccelerator(ui::Accelerator(ui::VKEY_RETURN, ui::EF_NONE));
   else
     RemoveAccelerator(ui::Accelerator(ui::VKEY_RETURN, ui::EF_NONE));
   SchedulePaint();
 }
 
 void TextButtonBase::SetText(const string16& text) {
+  if (text == text_)
+    return;
   text_ = text;
   SetAccessibleName(text);
   UpdateTextSize();
 }
 
 void TextButtonBase::SetFont(const gfx::Font& font) {
   font_ = font;
   UpdateTextSize();
 }
 
@@ skipping 559 matching lines @@
   // Windows may paint a dotted focus rect in
   // NativeTextButton::OnPaintFocusBorder. To avoid getting two focus
   // indications (A dotted rect and a highlighted border) only set is_focused on
   // non windows platforms.
   params->button.is_focused = HasFocus() &&
       (focusable() || IsAccessibilityFocusable());
 #endif
 }
 
 }  // namespace views