Merge 185069 "Enforce context refrence guards in WebGL extensions."

Source/core/html/canvas/WebGLExtension.cpp

 /*
  * 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
@@ skipping 11 matching lines @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "config.h"
 
 #include "core/html/canvas/WebGLExtension.h"
 
 namespace blink {
 
+WebGLExtensionScopedContext::WebGLExtensionScopedContext(WebGLExtension* extension)
+    : m_context(extension->m_context)
+{
+}
+
+WebGLExtensionScopedContext::~WebGLExtensionScopedContext()
+{
+}
+
+void WebGLExtensionScopedContext::trace(Visitor* visitor)
+{
+    visitor->trace(m_context);
+}
+
+
 WebGLExtension::WebGLExtension(WebGLRenderingContextBase* context)
     : m_context(context)
 {
 }
 
 WebGLExtension::~WebGLExtension()
 {
 }
 
 void WebGLExtension::trace(Visitor* visitor)
 {
     visitor->trace(m_context);
 }
 
 } // namespace blink