Determine if OffscreenCanvas is paintable in different rendering contexts

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

Index: third_party/WebKit/Source/core/offscreencanvas/OffscreenCanvas.cpp
diff --git a/third_party/WebKit/Source/core/offscreencanvas/OffscreenCanvas.cpp b/third_party/WebKit/Source/core/offscreencanvas/OffscreenCanvas.cpp
index 316d340d0bf159ad50a06f8032c4ad03143ffdbf..526b9fb656f544c1aa9ecb33fb014edb31cc774f 100644
--- a/third_party/WebKit/Source/core/offscreencanvas/OffscreenCanvas.cpp
+++ b/third_party/WebKit/Source/core/offscreencanvas/OffscreenCanvas.cpp
@@ -8,6 +8,7 @@
 #include "core/html/canvas/CanvasContextCreationAttributes.h"
 #include "core/html/canvas/CanvasRenderingContext.h"
 #include "core/html/canvas/CanvasRenderingContextFactory.h"
+#include "platform/graphics/ImageBuffer.h"
 #include "wtf/MathExtras.h"
 #include <memory>
 
@@ -109,6 +110,13 @@ bool OffscreenCanvas::originClean() const
     return m_originClean && !m_disableReadingFromCanvas;
 }
 
+bool OffscreenCanvas::isPaintable() const
+{
+    if (!m_context)
+        return ImageBuffer::canCreateImageBuffer(m_size);
+    return m_context->isPaintable();
+}
+
 DEFINE_TRACE(OffscreenCanvas)
 {
     visitor->trace(m_context);