Move GrContext::makeDrawContext to new GrContextPriv object
We don't want external clients to be able to call the wrapping makeDrawContext. The "creating" makeDrawContext needs to be public for external image filters.
The 3 specialized drawContext creators on GrContextPriv (to wrap backend objects) are also to be kept from public use and will be used to remove SkSurface::MakeRenderTargetDirect.
Split out of: https://codereview.chromium.org/2176333002/ (Remove SkSurface::MakeRenderTargetDirect)
TBR=bsalomon@google.com
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Review-Url: https://codereview.chromium.org/2211473002
7 files changed