Make GrTextContext be owned by the GrDrawContext

This CL makes the GrTextContext be owned (and hidden) by the GrDrawContext. This funnels all the drawText* calls through the GrDrawContext and hides the (dispreferred) GrPipelineBuilder drawText variant.

Some consequences of this are:

GrDrawContext now has to get the text drawing settings (i.e., SkDeviceProperties & useDFT). This means that we need a separate GrDrawContext for each combination of pixel geometry and DFT-use.

All the GrTextContext-derived classes now get a back pointer to the originating GrDrawContext so their method calls no longer take one.

Committed: https://skia.googlesource.com/skia/+/5b16e740fe6ab6d679083d06f07651602265081b

Review URL: https://codereview.chromium.org/1175553002
15 files changed