Keep ViewCaptureRule logic self-contained.

This will make it easier for other apps / processes to integrate the
ViewCapture logic into their integrated testing frameworks.

Bug: 270158224
Test: Verified that a zip file was generated properly and was able to be
loaded into go/web-hv properly.

Change-Id: Ib3e4a0b60497937b750126590071884882b22917
4 files changed