Implement wouldTaintOrigin and expose createPattern for OCRC2D on main thread

third_party/WebKit/Source/modules/offscreencanvas2d/OffscreenCanvasRenderingContext2D.cpp

 // Copyright 2016 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 "modules/offscreencanvas2d/OffscreenCanvasRenderingContext2D.h"
 
 #include "bindings/modules/v8/UnionTypesModules.h"
 #include "core/frame/ImageBitmap.h"
 #include "platform/graphics/ImageBuffer.h"
 #include "platform/graphics/StaticBitmapImage.h"
@@ skipping 29 matching lines @@
 {
     return getOffscreenCanvas()->setOriginTainted();
 }
 
 bool OffscreenCanvasRenderingContext2D::wouldTaintOrigin(CanvasImageSource* source, ExecutionContext* executionContext)
 {
     if (executionContext->isWorkerGlobalScope()) {
         // Currently, we only support passing in ImageBitmap as source image in
         // drawImage() or createPattern() in a OffscreenCanvas2d in worker.
         ASSERT(source->isImageBitmap());
-        // ImageBitmap wouldTaintOrigin doesn't consider destinationSecurityOrigin.
-        return source->wouldTaintOrigin(nullptr);
     }
 
-    // TODO(crbug.com/606925): implement wouldTaintOrigin for OffscreenCanvas2d
-    // on main thread
-    NOTIMPLEMENTED();
-    return true;
+    return CanvasRenderingContext::wouldTaintOrigin(source, executionContext->getSecurityOrigin());
 }
 
 int OffscreenCanvasRenderingContext2D::width() const
 {
     return getOffscreenCanvas()->width();
 }
 
 int OffscreenCanvasRenderingContext2D::height() const
 {
     return getOffscreenCanvas()->height();
@@ skipping 89 matching lines @@
     }
 #endif
 }
 
 bool OffscreenCanvasRenderingContext2D::isContextLost() const
 {
     return false;
 }
 
 }