I've looked at other CCT instrumentation tests, and it looks like we should be able to re-use our existing WebVR tests for CTA without too much work. It'll mainly involve having different setup steps for CTA vs CCT. I'll write up a design proposal in the near future.

The full implementation plan is available at https://docs.google.com/a/google.com/document/d/1Gn8eEuYwD3NTK3vbUWu5tGsFxPkzSUd3bvlT08MV3DE/edit?usp=sharing, but overall it looks like it will be quite simple to add support for this.

Updated implementation plan is available at https://docs.google.com/a/google.com/document/d/1BzcnHTXf5EuPvZMX7He6UiYIWoby7WveS-nhQa6Qyqc/edit?usp=sharing

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/57bd09b266854a20ea782c556381c6c3a6fea619

commit 57bd09b266854a20ea782c556381c6c3a6fea619
Author: bsheedy <bsheedy@chromium.org>
Date: Thu Aug 17 23:53:19 2017

Add VR test support for custom tabs and webapps

Refactors existing test code and adds new test rules to allow existing
VR instrumentation tests to run in CustomTabActivity and WebappActivity
in addition to ChromeTabbedActivity using JUnit4 test parameterization.

The additional support is only enabled on two tests in this CL so that
there isn't any significant impact on runtime on the capacity-crunched
bots.

Bug:  729828 
Change-Id: Ia25e35704b18925c68c6eacd4e824c07163c8913
Reviewed-on: https://chromium-review.googlesource.com/611773
Reviewed-by: John Budorick <jbudorick@chromium.org>
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Reviewed-by: Yoland Yan <yolandyan@chromium.org>
Reviewed-by: Michael Thiessen <mthiesse@chromium.org>
Commit-Queue: Brian Sheedy <bsheedy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#495386}
[modify] https://crrev.com/57bd09b266854a20ea782c556381c6c3a6fea619/build/android/findbugs_filter/findbugs_exclude.xml
[modify] https://crrev.com/57bd09b266854a20ea782c556381c6c3a6fea619/build/android/pylib/instrumentation/instrumentation_parser.py
[modify] https://crrev.com/57bd09b266854a20ea782c556381c6c3a6fea619/build/android/pylib/instrumentation/instrumentation_test_instance.py
[modify] https://crrev.com/57bd09b266854a20ea782c556381c6c3a6fea619/chrome/android/BUILD.gn
[modify] https://crrev.com/57bd09b266854a20ea782c556381c6c3a6fea619/chrome/android/javatests/src/org/chromium/chrome/browser/vr_shell/VrFeedbackInfoBarTest.java
[modify] https://crrev.com/57bd09b266854a20ea782c556381c6c3a6fea619/chrome/android/javatests/src/org/chromium/chrome/browser/vr_shell/VrInstallUpdateInfoBarTest.java
[modify] https://crrev.com/57bd09b266854a20ea782c556381c6c3a6fea619/chrome/android/javatests/src/org/chromium/chrome/browser/vr_shell/VrShellCompositorViewHolderTest.java
[modify] https://crrev.com/57bd09b266854a20ea782c556381c6c3a6fea619/chrome/android/javatests/src/org/chromium/chrome/browser/vr_shell/VrShellControllerInputTest.java
[modify] https://crrev.com/57bd09b266854a20ea782c556381c6c3a6fea619/chrome/android/javatests/src/org/chromium/chrome/browser/vr_shell/VrShellNativeUiTest.java
[modify] https://crrev.com/57bd09b266854a20ea782c556381c6c3a6fea619/chrome/android/javatests/src/org/chromium/chrome/browser/vr_shell/VrShellNavigationTest.java
[modify] https://crrev.com/57bd09b266854a20ea782c556381c6c3a6fea619/chrome/android/javatests/src/org/chromium/chrome/browser/vr_shell/VrShellTransitionTest.java
[rename] https://crrev.com/57bd09b266854a20ea782c556381c6c3a6fea619/chrome/android/javatests/src/org/chromium/chrome/browser/vr_shell/VrTestFramework.java
[modify] https://crrev.com/57bd09b266854a20ea782c556381c6c3a6fea619/chrome/android/javatests/src/org/chromium/chrome/browser/vr_shell/WebVrDeviceTest.java
[modify] https://crrev.com/57bd09b266854a20ea782c556381c6c3a6fea619/chrome/android/javatests/src/org/chromium/chrome/browser/vr_shell/WebVrInputTest.java
[modify] https://crrev.com/57bd09b266854a20ea782c556381c6c3a6fea619/chrome/android/javatests/src/org/chromium/chrome/browser/vr_shell/WebVrTabTest.java
[modify] https://crrev.com/57bd09b266854a20ea782c556381c6c3a6fea619/chrome/android/javatests/src/org/chromium/chrome/browser/vr_shell/WebVrTransitionTest.java
[add] https://crrev.com/57bd09b266854a20ea782c556381c6c3a6fea619/chrome/android/javatests/src/org/chromium/chrome/browser/vr_shell/rules/ChromeTabbedActivityVrTestRule.java
[add] https://crrev.com/57bd09b266854a20ea782c556381c6c3a6fea619/chrome/android/javatests/src/org/chromium/chrome/browser/vr_shell/rules/CustomTabActivityVrTestRule.java
[add] https://crrev.com/57bd09b266854a20ea782c556381c6c3a6fea619/chrome/android/javatests/src/org/chromium/chrome/browser/vr_shell/rules/VrActivityRestriction.java
[add] https://crrev.com/57bd09b266854a20ea782c556381c6c3a6fea619/chrome/android/javatests/src/org/chromium/chrome/browser/vr_shell/rules/VrActivityRestrictionRule.java
[add] https://crrev.com/57bd09b266854a20ea782c556381c6c3a6fea619/chrome/android/javatests/src/org/chromium/chrome/browser/vr_shell/rules/VrTestRule.java
[add] https://crrev.com/57bd09b266854a20ea782c556381c6c3a6fea619/chrome/android/javatests/src/org/chromium/chrome/browser/vr_shell/rules/WebappActivityVrTestRule.java
[modify] https://crrev.com/57bd09b266854a20ea782c556381c6c3a6fea619/chrome/android/javatests/src/org/chromium/chrome/browser/vr_shell/util/CardboardUtils.java
[modify] https://crrev.com/57bd09b266854a20ea782c556381c6c3a6fea619/chrome/android/javatests/src/org/chromium/chrome/browser/vr_shell/util/VrInfoBarUtils.java
[add] https://crrev.com/57bd09b266854a20ea782c556381c6c3a6fea619/chrome/android/javatests/src/org/chromium/chrome/browser/vr_shell/util/VrTestRuleUtils.java
[modify] https://crrev.com/57bd09b266854a20ea782c556381c6c3a6fea619/chrome/android/javatests/src/org/chromium/chrome/browser/vr_shell/util/VrTransitionUtils.java
[modify] https://crrev.com/57bd09b266854a20ea782c556381c6c3a6fea619/chrome/test/android/BUILD.gn
[add] https://crrev.com/57bd09b266854a20ea782c556381c6c3a6fea619/chrome/test/android/javatests/src/org/chromium/chrome/test/ChromeJUnit4RunnerDelegate.java