To properly test the functionality, following changes were needed
- Make RTCMTLVideoView compiliable for all cpu architectures not just arm64.
This is needed so that the test can run on any device and on simulator as well.
- Refactor RTCMTLVideoView to have mockable class methods.
The unittest class, RTCMTLVideoViewTests was designed to provide easy transition
to XCTest when the time comes for that.
To transition to XCTest it would suffice to inherit from XCTestCase and remove
the gtest methods.
BUG=webrtc:7079
Review-Url: https://codereview.webrtc.org/2723903003
Cr-Commit-Position: refs/heads/master@{#17014}
0ebe0199ac