Convert MessageBoxFlags class into an enum.

views/controls/message_box_view.cc

Index: views/controls/message_box_view.cc
diff --git a/views/controls/message_box_view.cc b/views/controls/message_box_view.cc
index 8216f2992cb0716a1bab404139a225164d283268..6c631c834182e89946e1b46dd91b44a0c60f2e76 100644
--- a/views/controls/message_box_view.cc
+++ b/views/controls/message_box_view.cc
@@ -130,7 +130,7 @@ void MessageBoxView::Init(int dialog_flags,
                           const string16& default_prompt) {
   message_label_->SetMultiLine(true);
   message_label_->SetAllowCharacterBreak(true);
-  if (dialog_flags & ui::MessageBoxFlags::kAutoDetectAlignment) {
+  if (dialog_flags & ui::MESSAGE_BOX_AUTO_DETECT_ALIGNMENT) {
     // Determine the alignment and directionality based on the first character
     // with strong directionality.
     base::i18n::TextDirection direction =
@@ -150,7 +150,7 @@ void MessageBoxView::Init(int dialog_flags,
     message_label_->SetHorizontalAlignment(Label::ALIGN_LEFT);
   }
 
-  if (dialog_flags & ui::MessageBoxFlags::kFlagHasPromptField) {
+  if (dialog_flags & ui::MESSAGE_BOX_HAS_PROMPT_FIELD) {
     prompt_field_ = new Textfield;
     prompt_field_->SetText(default_prompt);
   }