Add createGradient and createPattern to OffscreenCanvas2D in worker

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 23 matching lines @@
 bool OffscreenCanvasRenderingContext2D::originClean() const
 {
     return m_originClean;
 }
 
 void OffscreenCanvasRenderingContext2D::setOriginTainted()
 {
     m_originClean = false;
 }
 
-bool OffscreenCanvasRenderingContext2D::wouldTaintOrigin(CanvasImageSource* source)
+bool OffscreenCanvasRenderingContext2D::wouldTaintOrigin(CanvasImageSource* source, ScriptState* scriptState)
 {
+    if (scriptState->getExecutionContext()->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 false;
+    return true;
 }
 
 int OffscreenCanvasRenderingContext2D::width() const
 {
     return getOffscreenCanvas()->width();
 }
 
 int OffscreenCanvasRenderingContext2D::height() const
 {
     return getOffscreenCanvas()->height();
@@ skipping 83 matching lines @@
     }
 #endif
 }
 
 bool OffscreenCanvasRenderingContext2D::isContextLost() const
 {
     return false;
 }
 
 }