use the metadata on canvas instead of on device

skia/ext/platform_canvas.cc

Index: skia/ext/platform_canvas.cc
diff --git a/skia/ext/platform_canvas.cc b/skia/ext/platform_canvas.cc
index ec99dfe92a8f6a4541747729d907c52e5fd2e21b..c19464d8baaf5ec127d1c9f7f20907f48b4df4c7 100644
--- a/skia/ext/platform_canvas.cc
+++ b/skia/ext/platform_canvas.cc
@@ -77,9 +77,7 @@ std::unique_ptr<SkCanvas> CreateCanvas(const sk_sp<SkBaseDevice>& device,
 }
 
 SkMetaData& GetMetaData(const SkCanvas& canvas) {
-  SkBaseDevice* device = canvas.getDevice();
-  DCHECK(device != nullptr);
-  return device->getMetaData();
+  return const_cast<SkCanvas&>(canvas).getMetaData();
 }
 
 #if defined(OS_MACOSX)