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

chrome/browser/download/download_request_manager.cc

 // Copyright (c) 2006-2008 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/download/download_request_manager.h"
 
 #include "base/message_loop.h"
 #include "base/thread.h"
 #include "chrome/browser/download/download_request_dialog_delegate.h"
 #include "chrome/browser/tab_contents/navigation_controller.h"
@@ skipping 40 matching lines @@
 
   if (status_ != DownloadRequestManager::ALLOW_ALL_DOWNLOADS &&
       status_ != DownloadRequestManager::DOWNLOADS_NOT_ALLOWED) {
     // Revert to default status.
     host_->Remove(this);
     // WARNING: We've been deleted.
     return;
   }
 }
 
-void DownloadRequestManager::TabDownloadState::PromptUserForDownload(
+bool DownloadRequestManager::TabDownloadState::PromptUserForDownload(
     TabContents* tab,
     DownloadRequestManager::Callback* callback) {
   callbacks_.push_back(callback);
 
   if (is_showing_prompt())
-    return;  // Already showing prompt.
+    return true;  // Already showing prompt.
 
   if (DownloadRequestManager::delegate_) {
     NotifyCallbacks(DownloadRequestManager::delegate_->ShouldAllowDownload());
   } else {
     dialog_delegate_ = DownloadRequestDialogDelegate::Create(tab, this);
+    if (!dialog_delegate_)
+      return false;
   }
+  return true;
 }
 
 void DownloadRequestManager::TabDownloadState::Cancel() {
   NotifyCallbacks(false);
 }
 
 void DownloadRequestManager::TabDownloadState::Accept() {
   NotifyCallbacks(true);
 }
 
@@ skipping 170 matching lines @@
     case ALLOW_ONE_DOWNLOAD:
       state->set_download_status(PROMPT_BEFORE_DOWNLOAD);
       ScheduleNotification(callback, true);
       break;
 
     case DOWNLOADS_NOT_ALLOWED:
       ScheduleNotification(callback, false);
       break;
 
     case PROMPT_BEFORE_DOWNLOAD:
-      state->PromptUserForDownload(effective_tab, callback);
+      // Conceivably, for some reason (e.g., already have another tab-modal
+      // dialog up), we may not be able display a prompt. In that case, default
+      // to denial.
+      if (!state->PromptUserForDownload(effective_tab, callback))
+        ScheduleNotification(callback, false);
       break;
 
     default:
       NOTREACHED();
   }
 }
 
 void DownloadRequestManager::ScheduleNotification(Callback* callback,
                                                   bool allow) {
   if (io_loop_) {
@@ skipping 16 matching lines @@
 
 void DownloadRequestManager::Remove(TabDownloadState* state) {
   DCHECK(state_map_.find(state->controller()) != state_map_.end());
   state_map_.erase(state->controller());
   delete state;
 }
 
 // static
 DownloadRequestManager::TestingDelegate* DownloadRequestManager::delegate_ =
     NULL;