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

chrome/browser/login_prompt_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/login_prompt.h"
 #import "chrome/browser/login_prompt_mac.h"
 
 #include "app/l10n_util.h"
 #include "base/mac_util.h"
 #include "base/message_loop.h"
@@ skipping 64 matching lines @@
                                        const std::wstring& password) {
     [sheet_controller_ autofillLogin:base::SysWideToNSString(username)
                             password:base::SysWideToNSString(password)];
   }
 
   // LoginHandler:
   virtual void BuildViewForPasswordManager(PasswordManager* manager,
                                            std::wstring explanation) {
     DCHECK(MessageLoop::current() == ui_loop_);
 
+    TabContents* requesting_contents = GetTabContentsForLogin();
+    DCHECK(requesting_contents);
+
+    // If something goes wrong (e.g., there's already a tab-modal sheet up),
+    // cancel the authorization.
+    if (!requesting_contents ||
+        !requesting_contents->CanCreateConstrainedDialog()) {
+      CancelAuth();
+      return;
+    }
+
     // Load nib here instead of in constructor.
     sheet_controller_ = [[[LoginHandlerSheet alloc]
         initWithLoginHandler:this] autorelease];
     init([sheet_controller_ window], sheet_controller_,
           @selector(sheetDidEnd:returnCode:contextInfo:));
 
     SetModel(manager);
 
     [sheet_controller_ setExplanation:base::SysWideToNSString(explanation)];
 
@@ skipping 267 matching lines @@
        sizeToFitFixedWidthTextField:explanationField_];
 
   // Resize the window (no shifting needed due to window layout).
   NSSize windowDelta = NSMakeSize(0, explanationShift);
   [GTMUILocalizerAndLayoutTweaker
       resizeWindowWithoutAutoResizingSubViews:[self window]
                                         delta:windowDelta];
 }
 
 @end