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

cc/raster/gpu_raster_buffer_provider.cc

Index: cc/raster/gpu_raster_buffer_provider.cc
diff --git a/cc/raster/gpu_raster_buffer_provider.cc b/cc/raster/gpu_raster_buffer_provider.cc
index aaf2ea4ff3178b6c63661718b2f05792c24db58e..dbe72d62dc03e169f21caafa6067fe5c964e03c6 100644
--- a/cc/raster/gpu_raster_buffer_provider.cc
+++ b/cc/raster/gpu_raster_buffer_provider.cc
@@ -60,8 +60,8 @@ static sk_sp<SkPicture> PlaybackToPicture(
 
   // Play back raster_source into temp SkPicture.
   SkPictureRecorder recorder;
-  SkCanvas* canvas =
-      recorder.beginRecording(resource_size.width(), resource_size.height());
+  sk_sp<SkCanvas> canvas = sk_ref_sp(
+      recorder.beginRecording(resource_size.width(), resource_size.height()));
   canvas->save();
 
   // The GPU image decode controller assumes that Skia is done with an image
@@ -73,7 +73,7 @@ static sk_sp<SkPicture> PlaybackToPicture(
   // later picture rasterization.
   RasterSource::PlaybackSettings settings = playback_settings;
   settings.use_image_hijack_canvas = false;
-  raster_source->PlaybackToCanvas(canvas, raster_full_rect, playback_rect,
+  raster_source->PlaybackToCanvas(canvas.get(), raster_full_rect, playback_rect,
                                   scales, settings);
   canvas->restore();
   return recorder.finishRecordingAsPicture();