Change call-sites now that SkCanvas is not ref-counted

skia/ext/bitmap_platform_device_cairo.cc

Index: skia/ext/bitmap_platform_device_cairo.cc
diff --git a/skia/ext/bitmap_platform_device_cairo.cc b/skia/ext/bitmap_platform_device_cairo.cc
index 231c3a8b4a4051cc63fc86cfec71321bf3cd2215..093719e1cad9a7fe1a05a941087d7a3ec331ca61 100644
--- a/skia/ext/bitmap_platform_device_cairo.cc
+++ b/skia/ext/bitmap_platform_device_cairo.cc
@@ -166,8 +166,11 @@ cairo_t* BitmapPlatformDevice::BeginPlatformPaint(
 
 // PlatformCanvas impl
 
-SkCanvas* CreatePlatformCanvas(int width, int height, bool is_opaque,
-                               uint8_t* data, OnFailureType failureType) {
+std::unique_ptr<SkCanvas> CreatePlatformCanvas(int width,
+                                               int height,
+                                               bool is_opaque,
+                                               uint8_t* data,
+                                               OnFailureType failureType) {
   sk_sp<SkBaseDevice> dev(
       BitmapPlatformDevice::Create(width, height, is_opaque, data));
   return CreateCanvas(dev, failureType);