Remove SkSurface::MakeRenderTargetDirect

Remove SkSurface::MakeRenderTargetDirect

split into:
https://codereview.chromium.org/2182543003/ (Move prepareForExternalIO from GrRenderTarget to GrDrawContext)
https://codereview.chromium.org/2187573002/ (Reduce usage of MakeRenderTargetDirect)
https://codereview.chromium.org/2186073002/ (Rename GrContext's newDrawContext & drawContext to makeDrawContext)
https://codereview.chromium.org/2178353005/ (Remove use of MakeRenderTargetDirect from view system)
https://codereview.chromium.org/2198433003/ (Remove some ancillary users of SkSurface::MakeRenderTargetDirect)
https://codereview.chromium.org/2208483004/ (Remove GrRenderTarget member variable from SkGpuDevice)
https://codereview.chromium.org/2211473002/ (Move GrContext::makeDrawContext to new GrContextPriv object)

TBR=bsalomon@google.com

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Review-Url: https://codereview.chromium.org/2176333002