Builder class for SkLayerRasterizer.

Provide builder class to make SkLayerRasterizer immutable. We have to keep the
addLayer() methods for now because they are used in Chrome. They will be removed
once this changed has been rolled into Chrome.
An added benefit of this is that this class can only be allocated on the heap.

BUG=skia:2187
R=reed@google.com, scroggo@google.com, mtklein@google.com

Author: dominikg@chromium.org

Review URL: https://codereview.chromium.org/176873004

git-svn-id: http://skia.googlecode.com/svn/trunk@13590 2bbb7eff-a529-9590-31e7-b0007b416f81
8 files changed