Fix a minor issue in OffscreenCanvas.drawImage

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/fileapi/Blob.h"
 #include "core/html/ImageData.h"
 #include "core/html/canvas/CanvasAsyncBlobCreator.h"
@@ skipping 75 matching lines @@
   return image;
 }
 
 PassRefPtr<Image> OffscreenCanvas::getSourceImageForCanvas(
     SourceImageStatus* status,
     AccelerationHint hint,
     SnapshotReason reason,
     const FloatSize& size) const {
   if (!m_context) {
     *status = InvalidSourceImageStatus;
-    return nullptr;
+    sk_sp<SkSurface> surface =
+        SkSurface::MakeRasterN32Premul(m_size.width(), m_size.height());
+    return surface ? StaticBitmapImage::create(surface->makeImageSnapshot())
+                   : nullptr;
   }
   if (!size.width() || !size.height()) {
     *status = ZeroSizeCanvasSourceImageStatus;
     return nullptr;
   }
   RefPtr<Image> image = m_context->getImage(hint, reason);
   if (!image) {
     *status = InvalidSourceImageStatus;
   } else {
     *status = NormalSourceImageStatus;
@@ skipping 133 matching lines @@
   return resolver->promise();
 }
 
 DEFINE_TRACE(OffscreenCanvas) {
   visitor->trace(m_context);
   visitor->trace(m_executionContext);
   EventTargetWithInlineData::trace(visitor);
 }
 
 }  // namespace blink