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

chrome/browser/cocoa/download_request_dialog_delegate_mac.mm

Index: chrome/browser/cocoa/download_request_dialog_delegate_mac.mm
diff --git a/chrome/browser/cocoa/download_request_dialog_delegate_mac.mm b/chrome/browser/cocoa/download_request_dialog_delegate_mac.mm
index 4f5e29acba60df6e6c48806ec11d005edfdf6fd4..bb9e846a89ee5c3afedb1002560452e42abcdb1f 100644
--- a/chrome/browser/cocoa/download_request_dialog_delegate_mac.mm
+++ b/chrome/browser/cocoa/download_request_dialog_delegate_mac.mm
@@ -37,10 +37,18 @@
 @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);
 }
 
@@ -81,7 +89,8 @@ void DownloadRequestDialogDelegateMac::CloseWindow() {
 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_) {
@@ -95,10 +104,18 @@ void DownloadRequestDialogDelegateMac::DeleteDelegate() {
 
 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;
 }