Mac: make save/open dialogs operate as tab-modal sheets....

chrome/browser/cocoa/download_request_dialog_delegate_mac.mm

 // Copyright (c) 2009 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 "chrome/browser/cocoa/download_request_dialog_delegate_mac.h"
 
 #import <Cocoa/Cocoa.h>
 
 #include "app/l10n_util_mac.h"
 #include "app/message_box_flags.h"
@@ skipping 19 matching lines @@
   return self;
 }
 - (void)alertDidEnd:(NSAlert *)alert
          returnCode:(int)returnCode
         contextInfo:(void *)contextInfo {
   target_->SheetDidEnd(returnCode);
 }
 @end
 
 
+// Return value passed to the end-sheet routine to indicate that the sheet was
+// ended by |DeleteDelegate()|. This just needs to be some value never used by
+// Apple as a return value for the sheet.
+static int kClosedByDelegate = 658042027;
+
 // static
 DownloadRequestDialogDelegate* DownloadRequestDialogDelegate::Create(
     TabContents* tab,
     DownloadRequestManager::TabDownloadState* host) {
+  if (!tab->CanCreateConstrainedDialog())
+    return NULL;
+
   return new DownloadRequestDialogDelegateMac(tab, host);
 }
 
 DownloadRequestDialogDelegateMac::DownloadRequestDialogDelegateMac(
     TabContents* tab,
     DownloadRequestManager::TabDownloadState* host)
     : DownloadRequestDialogDelegate(host),
       ConstrainedWindowMacDelegateSystemSheet(
           [[[SheetCallback alloc] initWithTarget:this] autorelease],
           @selector(alertDidEnd:returnCode:contextInfo:)),
@@ skipping 20 matching lines @@
   window_ = tab->CreateConstrainedDialog(this);
 }
 
 void DownloadRequestDialogDelegateMac::CloseWindow() {
   window_->CloseConstrainedWindow();
 }
 
 void DownloadRequestDialogDelegateMac::DeleteDelegate() {
   if (is_sheet_open()) {
     // Close sheet if it's still open.
-    [NSApp endSheet:[(NSAlert*)sheet() window]];  // calls SheetDidEnd().
+    [NSApp endSheet:[(NSAlert*)sheet() window]
+         returnCode:kClosedByDelegate];  // Calls SheetDidEnd().
     DCHECK(responded_);
   }
   if (!responded_) {
     // Happens if the sheet was never visible.
     responded_ = true;
     DoCancel();
   }
   DCHECK(!host_);
   delete this;
 }
 
 void DownloadRequestDialogDelegateMac::SheetDidEnd(int returnCode) {
   DCHECK(!responded_);
+  responded_ = true;
   if (returnCode == NSAlertFirstButtonReturn) {
     DoAccept();
   } else {
     DoCancel();
+
+    // If this ended in a "normal" way, i.e., the user pressing one of the
+    // buttons, we still have to clean up the window (and the delegate). If, on
+    // the other hand, the window was ended by |CloseConstrainedWindow()| (which
+    // caused this routine to be called), then we *must* not try to do that
+    // again.
+    if (returnCode != kClosedByDelegate)
+      CloseWindow();
   }
-  responded_ = true;
 }