support direct writing to top layer, and hide getTopLayer()
this should remove many of the chrome callers that today call
accessBitmap on the toplayer, so they can read/write those pixels.
The ultimate fix will be to support custom allocation of raster layers
(via GDI/cairo/mac) so we can remove PlatformDevice subclassing in
skia/ext
BUG=skia:
R=bsalomon@google.com, scroggo@google.com
Review URL: https://codereview.chromium.org/197433002
git-svn-id: http://skia.googlecode.com/svn/trunk@13774 2bbb7eff-a529-9590-31e7-b0007b416f81
13 files changed