Optionally clear PlatformCanvas instances.

skia/ext/vector_platform_device_skia.cc

Index: skia/ext/vector_platform_device_skia.cc
===================================================================
--- skia/ext/vector_platform_device_skia.cc	(revision 126450)
+++ skia/ext/vector_platform_device_skia.cc	(working copy)
@@ -53,7 +53,10 @@
 #endif
   raster_surface_->unref();  // SkRefPtr and create both took a reference.
 
+#if defined(OS_WIN) || defined(OS_MACOSX)

[vandebo (ex-Chrome), 2012/03/14 23:38:29]

I comment wouldn't hurt here.

[Jeff Timanus, 2012/03/15 19:01:28]

Done.

   SkCanvas canvas(raster_surface_.get());

[vandebo (ex-Chrome), 2012/03/14 23:38:29]

nit: Why is/was this here?

[Jeff Timanus, 2012/03/15 19:01:28]

I noticed this, and was also confused.  I left it as is, because I wanted to
minimize any impact this change may have had.  

It was introduced when the PDF back-end was brought into chrome.  See
http://src.chromium.org/viewvc/chrome?view=rev&revision=80873

[vandebo (ex-Chrome), 2012/03/15 20:40:57]

Ahh - in that revision, the device is cleared to black using the canvas.  At
some point that was removed.

+  canvas.clear(SkColorSetARGB(0, 0, 0, 0));
+#endif
   return raster_surface_->BeginPlatformPaint();
 }