Adding nullability support to ImageBitmapRenderingContext.transferImageBitmap

third_party/WebKit/Source/modules/imagebitmap/ImageBitmapRenderingContext.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/imagebitmap/ImageBitmapRenderingContext.h"
 
 #include "bindings/modules/v8/RenderingContext.h"
 #include "core/frame/ImageBitmap.h"
 #include "platform/graphics/GraphicsContext.h"
 #include "platform/graphics/StaticBitmapImage.h"
 #include "third_party/skia/include/core/SkImage.h"
 #include "third_party/skia/include/core/SkSurface.h"
 
 namespace blink {
 
 ImageBitmapRenderingContext::ImageBitmapRenderingContext(HTMLCanvasElement* canvas, CanvasContextCreationAttributes attrs, Document& document)
     : CanvasRenderingContext(canvas)
     , m_hasAlpha(attrs.alpha())
 { }
 
 ImageBitmapRenderingContext::~ImageBitmapRenderingContext() { }
 
 void ImageBitmapRenderingContext::setCanvasGetContextResult(RenderingContext& result)
 {
     result.setImageBitmapRenderingContext(this);
 }
 
 void ImageBitmapRenderingContext::transferFromImageBitmap(ImageBitmap* imageBitmap)
 {
+    if (!imageBitmap) {
+        m_image.release();
+        return;
+    }
+
     m_image = imageBitmap->bitmapImage();
     if (!m_image)
         return;
 
     RefPtr<SkImage> skImage = m_image->imageForCurrentFrame();
     if (skImage->isTextureBacked()) {
         // TODO(junov): crbug.com/585607 Eliminate this readback and use an ExternalTextureLayer
         sk_sp<SkSurface> surface = SkSurface::MakeRasterN32Premul(skImage->width(), skImage->height());
         if (!surface) {
             // silent failure
@@ skipping 24 matching lines @@
         return nullptr;
     return new ImageBitmapRenderingContext(canvas, attrs, document);
 }
 
 void ImageBitmapRenderingContext::stop()
 {
     m_image.clear();
 }
 
 } // blink