WTF: Make PassOwnPtr<T> move-only.

third_party/WebKit/Source/core/offscreencanvas/OffscreenCanvas.cpp

 // Copyright 2015 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 "core/offscreencanvas/OffscreenCanvas.h"
 
 #include "core/dom/ExceptionCode.h"
 #include "core/html/canvas/CanvasContextCreationAttributes.h"
 #include "core/html/canvas/CanvasRenderingContext.h"
 #include "core/html/canvas/CanvasRenderingContextFactory.h"
@@ skipping 69 matching lines @@
 {
     ASSERT(type < CanvasRenderingContext::ContextTypeCount);
     return renderingContextFactories()[type].get();
 }
 
 void OffscreenCanvas::registerRenderingContextFactory(PassOwnPtr<CanvasRenderingContextFactory> renderingContextFactory)
 {
     CanvasRenderingContext::ContextType type = renderingContextFactory->getContextType();
     ASSERT(type < CanvasRenderingContext::ContextTypeCount);
     ASSERT(!renderingContextFactories()[type]);
-    renderingContextFactories()[type] = renderingContextFactory;
+    renderingContextFactories()[type] = std::move(renderingContextFactory);
 }
 
 DEFINE_TRACE(OffscreenCanvas)
 {
     visitor->trace(m_context);
     visitor->trace(m_canvas);
 }
 
 } // namespace blink