In LabelButton::SetIsDefault: ~ is bitwise NOT, not !.

ui/views/controls/button/label_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/label_button.h"
 
 #include "base/logging.h"
 #include "grit/ui_resources.h"
 #include "ui/base/animation/throb_animation.h"
 #include "ui/base/resource/resource_bundle.h"
@@ skipping 110 matching lines @@
 void LabelButton::SetIsDefault(bool is_default) {
   if (is_default == is_default_)
     return;
   is_default_ = is_default;
   ui::Accelerator accel(ui::VKEY_RETURN, ui::EF_NONE);
   is_default_ ? AddAccelerator(accel) : RemoveAccelerator(accel);
 
   // STYLE_BUTTON uses bold text to indicate default buttons.
   if (style_ == STYLE_BUTTON) {
     int style = label_->font().GetStyle();
-    style = is_default ? style | gfx::Font::BOLD : style & !gfx::Font::BOLD;
+    style = is_default ? style | gfx::Font::BOLD : style & ~gfx::Font::BOLD;
     label_->SetFont(label_->font().DeriveFont(0, style));
   }
 }
 
 void LabelButton::SetStyle(ButtonStyle style) {
   // Use the new button style instead of the native button style.
   // TODO(msw): Officialy deprecate and remove STYLE_NATIVE_TEXTBUTTON.
   if (DialogDelegate::UseNewStyle() && style == STYLE_NATIVE_TEXTBUTTON)
     style = STYLE_BUTTON;
 
@@ skipping 221 matching lines @@
   return ui::NativeTheme::kNormal;
 }
 
 ui::NativeTheme::State LabelButton::GetForegroundThemeState(
     ui::NativeTheme::ExtraParams* params) const {
   GetExtraParams(params);
   return ui::NativeTheme::kHovered;
 }
 
 }  // namespace views