MacViews: Exploring removal of window-modal sheets.

ui/views/widget/native_widget_mac.mm

 // Copyright 2014 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/widget/native_widget_mac.h"
 
 #import <Cocoa/Cocoa.h>
 
 #include <utility>
 
@@ skipping 27 matching lines @@
   base::scoped_nsobject<NSAnimation> animation_;
 }
 
 + (void)closeWindowWithAnimation:(NSWindow*)window;
 
 @end
 
 namespace views {
 namespace {
 
+bool SheetsEnabled() {
+  return false;
+}
+
 NSInteger StyleMaskForParams(const Widget::InitParams& params) {
   // If the Widget is modal, it will be displayed as a sheet. This works best if
   // it has NSTitledWindowMask. For example, with NSBorderlessWindowMask, the
   // parent window still accepts input.
-  if (params.delegate &&
+  if (SheetsEnabled() && params.delegate &&
       params.delegate->GetModalType() == ui::MODAL_TYPE_WINDOW)
     return NSTitledWindowMask;
 
   // TODO(tapted): Determine better masks when there are use cases for it.
   if (params.remove_standard_frame)
     return NSBorderlessWindowMask;
 
   if (params.type == Widget::InitParams::TYPE_WINDOW) {
     return NSTitledWindowMask | NSClosableWindowMask |
            NSMiniaturizableWindowMask | NSResizableWindowMask |
@@ skipping 26 matching lines @@
   id<NSWindowDelegate> window_delegate = [window delegate];
   if ([window_delegate respondsToSelector:@selector(nativeWidgetMac)]) {
     ViewsNSWindowDelegate* delegate =
         base::mac::ObjCCastStrict<ViewsNSWindowDelegate>(window_delegate);
     return [delegate nativeWidgetMac]->bridge_.get();
   }
   return nullptr;  // Not created by NativeWidgetMac.
 }
 
 bool NativeWidgetMac::IsWindowModalSheet() const {
-  return bridge_ && bridge_->parent() &&
+  return SheetsEnabled() && bridge_ && bridge_->parent() &&
          GetWidget()->widget_delegate()->GetModalType() ==
              ui::MODAL_TYPE_WINDOW;
 }
 
 void NativeWidgetMac::OnWindowDestroyed() {
   DCHECK(bridge_);
   bridge_.reset();
   delegate_->OnNativeWidgetDestroyed();
   if (ownership_ == Widget::InitParams::NATIVE_WIDGET_OWNS_WIDGET)
     delete this;
@@ skipping 670 matching lines @@
   [[ViewsNSWindowCloseAnimator alloc] initWithWindow:window];
 }
 
 - (void)animationDidEnd:(NSAnimation*)animation {
   [window_ close];
   [animation_ setDelegate:nil];
   [self release];
 }
 
 @end