Add missing null pointer check in HTMLCanvasElement.cpp

third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp

Index: third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp
diff --git a/third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp b/third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp
index b23ea4ea0c0b79402453575627dcf93abafebb63..2bf68aa49274532e3c2b8c46b49beb36193c3372 100644
--- a/third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp
+++ b/third_party/WebKit/Source/core/html/HTMLCanvasElement.cpp
@@ -115,7 +115,7 @@ sk_sp<SkImage> createTransparentSkImage(const IntSize& size) {
   DCHECK(ImageBuffer::canCreateImageBuffer(size));
   sk_sp<SkSurface> surface =
       SkSurface::MakeRasterN32Premul(size.width(), size.height());
-  return surface->makeImageSnapshot();
+  return surface ? surface->makeImageSnapshot() : nullptr;
 }
 
 PassRefPtr<Image> createTransparentImage(const IntSize& size) {