Rename "master context" to "primary context"

Bug: chromium:1101491
Bug: b/161896447

Use more inclusive language.

Change-Id: I32b312b7ccffc1a4aab88450595bec09a2fa031b
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/306943
Commit-Queue: Leon Scroggins <scroggo@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Auto-Submit: Leon Scroggins <scroggo@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
1 file changed