Fix browser hang due to plugin deadlock...

chrome/test/ui/npapi_uitest.cc

 // 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.
 
 // windows headers
 #include <windows.h>
 #include <shellapi.h>
 #include <shlobj.h>
 #include <atlbase.h>
 #include <comutil.h>
@@ skipping 266 matching lines @@
 // Test checking the privacy mode is on.
 TEST_F(NPAPIIncognitoTester, PrivateEnabled) {
   if (UITest::in_process_renderer())
     return;
 
   GURL url = GetTestUrl(L"npapi", L"private.html?secure");
   NavigateToURL(url);
   WaitForFinish("private", "1", url, kTestCompleteCookie,
                 kTestCompleteSuccess, kShortWaitTimeout);
 }
+
+// Test a browser hang due to special case of multiple
+// plugin instances indulged in sync calls across renderer.
+TEST_F(NPAPIVisiblePluginTester, MultipleInstancesSyncCalls) {
+  if (UITest::in_process_renderer())
+    return;
+
+  GURL url = GetTestUrl(L"npapi", L"multiple_instances_sync_calls.html");
+  NavigateToURL(url);
+  WaitForFinish("multiple_instances_sync_calls", "1", url, kTestCompleteCookie,
+                kTestCompleteSuccess, kShortWaitTimeout);
+}
+