Don't show FileManagerDialog if another FileManagerDialog is shown in the same tab.

chrome/browser/ui/views/file_manager_dialog_unittest.cc

 // Copyright (c) 2011 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/ui/views/file_manager_dialog.h"
 
 #include "base/file_path.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 class FileManagerDialogTest : public testing::Test {
  public:
   static FileManagerDialog* CreateDialog(SelectFileDialog::Listener* listener,
                                          int32 tab_id) {
     FileManagerDialog* dialog = new FileManagerDialog(listener);
     // Simulate the dialog opening.
+    EXPECT_FALSE(FileManagerDialog::PendingExists(tab_id));
     dialog->AddPending(tab_id);
+    EXPECT_TRUE(FileManagerDialog::PendingExists(tab_id));
     return dialog;
   }
 };
 
 // Client of a FileManagerDialog that deletes itself whenever the dialog
 // is closed.
 class SelfDeletingClient : public SelectFileDialog::Listener {
  public:
   explicit SelfDeletingClient(int32 tab_id) {
     dialog_ = FileManagerDialogTest::CreateDialog(this, tab_id);
@@ skipping 16 matching lines @@
 
 TEST_F(FileManagerDialogTest, FileManagerDialogMemory) {
   const int32 kTabId = 123;
   // Registers itself with an internal map, so we don't need the pointer,
   // and it would be unused anyway.
   new SelfDeletingClient(kTabId);
   // Ensure we don't crash or trip an Address Sanitizer warning about
   // use-after-free.
   FileManagerDialog::OnFileSelected(kTabId, FilePath(), 0);
 }