This test will load traces and cycle through a set of frames.

The new tests are:

    TracePerfTest.Run/gl_trex_200_210
    TracePerfTest.Run/gl_trex_800_810
    TracePerfTest.Run/gl_trex_900_910
    TracePerfTest.Run/gl_trex_1300_1310

To download the traces, you must be granted access and authenticate
with the cloud.  See the steps in RestrictedTraces.md for this.

Then add the following to the end of your .gclient file:

    "custom_vars": {
      "checkout_angle_internal":"True"
    },

And run `glcient runhooks`.

To enable building the test, add the following GN arg:

    build_angle_trace_perf_tests = true

See the new markdown document for ways to execute the tests.

Bug: angleproject:3630
Change-Id: Ic25cd94fb36b35fcf187e88d3bf9548c65f59755
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1949605
Commit-Queue: Cody Northrop <cnorthrop@google.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>