Make CanvasPainter raster directly to an SkBitmap

ui/compositor/paint_context.h

Index: ui/compositor/paint_context.h
diff --git a/ui/compositor/paint_context.h b/ui/compositor/paint_context.h
index b9c51dd386a3dca5caf7daa4d15ea1a541f18511..5ca65e755570f89c0029aa87817c6232b63bf4f5 100644
--- a/ui/compositor/paint_context.h
+++ b/ui/compositor/paint_context.h
@@ -65,6 +65,8 @@ class COMPOSITOR_EXPORT PaintContext {
 
   const gfx::Rect& InvalidationForTesting() const { return invalidation_; }
 
+  float device_scale_factor() const { return device_scale_factor_; }

[danakj, 2017/02/14 21:37:26]

It doesn't look like you need to add this if u store the raster scale. My
thought is that this API is intentionally left bare so it is very clear to go
thru a *Recorder to do anything, and PaintRecorder has a gfx::Canvas with a
scale on it.

+
  private:
   // The Recorder classes need access to the internal canvas and friends, but we
   // don't want to expose them on this class so that people must go through the