Add support for hardware buffers with protected content

Use EGL_EXT_protected_content extension if present to render
AHardwareBuffer with AHARDWAREBUFFER_USAGE_PROTECTED_CONTENT.

Bug: skia:
Change-Id: I1a5fa4cdc8f432b89ae9ef889175b50a25b846e0
Reviewed-on: https://skia-review.googlesource.com/149803
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Stan Iliev <stani@google.com>
2 files changed