--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/WebCore/bindings/js/JSMainThreadExecState.h	Fri Sep 17 09:02:29 2010 +0300
@@ -0,0 +1,84 @@
+/*
+ * Copyright (C) 2010 Google Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
+ * THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef JSMainThreadExecState_h
+#define JSMainThreadExecState_h
+
+#include <JSDOMBinding.h>
+#ifndef NDEBUG
+#include <wtf/MainThread.h>
+#endif
+#include <wtf/Noncopyable.h>
+
+namespace WebCore {
+
+class JSMainThreadExecState : public Noncopyable {
+public:
+    static JSC::ExecState* currentState()
+    { 
+        ASSERT(WTF::isMainThread());
+        return s_mainThreadState;
+    };
+    
+    static JSC::JSValue call(JSC::ExecState* exec, JSC::JSValue functionObject, JSC::CallType callType, const JSC::CallData& callData, JSC::JSValue thisValue, const JSC::ArgList& args)
+    {
+        JSMainThreadExecState currentState(exec);
+        return JSC::call(exec, functionObject, callType, callData, thisValue, args);
+    };
+
+    static JSC::Completion evaluate(JSC::ExecState* exec, JSC::ScopeChain& chain, const JSC::SourceCode& source, JSC::JSValue thisValue)
+    {
+        JSMainThreadExecState currentState(exec);
+        return JSC::evaluate(exec, chain, source, thisValue);
+    };
+
+protected:
+    explicit JSMainThreadExecState(JSC::ExecState* exec)
+        : m_previousState(s_mainThreadState)
+    {
+        ASSERT(WTF::isMainThread());
+        s_mainThreadState = exec;
+    };
+    
+    ~JSMainThreadExecState()
+    {
+        ASSERT(WTF::isMainThread());
+        s_mainThreadState = m_previousState;
+    }
+
+private:
+    static JSC::ExecState* s_mainThreadState;
+    JSC::ExecState* m_previousState;
+};
+
+// Null state prevents origin security checks.
+class JSMainThreadNullState : private JSMainThreadExecState {
+public:
+    explicit JSMainThreadNullState() : JSMainThreadExecState(0) {};
+};
+
+} // namespace WebCore
+
+#endif // JSMainThreadExecState_h