[skcapture] add initial plumbing for getting SkCapture data from clients
This CL starts adding SkCaptureManager and SkCaptureCanvas references across Skia:
* Providing an SkCapture factory for Surfaces to call on when capture is enabled.
* Creating start and stop APIs for capture on the Context
* Creating an external_client test file
Change-Id: I42ccfaa71a3e3345d5661eb1d87e683e2c8d6346
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/1004621
Reviewed-by: Michael Ludwig <michaelludwig@google.com>
Commit-Queue: Jorge Betancourt <jmbetancourt@google.com>
24 files changed
