Updated documentation for representative perf tests

Added more instructions on skipping representative perf tests stories.

Bug: chromium:1044705
Change-Id: Ic17b8ccbf345f4be207e0aa25c9a4fdfb0b1350c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2035855
Commit-Queue: Behdad Bakhshinategh <behdadb@chromium.org>
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>
Cr-Commit-Position: refs/heads/master@{#741213}

docs/gpu/pixel_wrangling.md

@@ -238,9 +238,8 @@ shift, and a calendar appointment.
         by Telemetry, rather than a Gtest harness. The tests and their
         expectations are contained in [src/content/test/gpu/gpu_tests/test_expectations] . See
         for example <code>[webgl_conformance_expectations.txt]</code>,
-        <code>[gpu_process_expectations.txt]</code>,
-        <code>[pixel_expectations.txt]</code> and
-        [rendering_representative_perf_tests].
+        <code>[gpu_process_expectations.txt]</code> and
+        <code>[pixel_expectations.txt]</code>.
     1.  See the header of the file a list of modifiers to specify a bot
         configuration. It is possible to specify OS (down to a specific
         version, say, Windows 7 or Mountain Lion), GPU vendor
@@ -255,6 +254,8 @@ shift, and a calendar appointment.
         close the Chromium tree.
     1.  Please read the section on [stamping out flakiness] for motivation on
         how important it is to eliminate flakiness rather than hiding it.
+    1. For failures of rendering_representative_perf_tests please refer to its
+    [instructions on updating expectations][rendering_representative_perf_tests].
 1.  For the remaining Gtest-style tests, use the [`DISABLED_`
     modifier][gtest-DISABLED] to suppress any failures if necessary.
 

docs/testing/rendering_representative_perf_tests.md

@@ -41,4 +41,10 @@ of [`src/testing/scripts/representative_perf_test_data/representatives_frame_tim
 
 To skip any of the tests, update
 [`src/tools/perf/expectations.config`](../../tools/perf/expectations.config) and
-add the story under rendering benchmark.
\ No newline at end of file
+add the story under rendering benchmark (Examples [1](https://chromium-review.googlesource.com/c/chromium/src/+/2055681), [2](https://chromium-review.googlesource.com/c/chromium/src/+/1901357)).
+This expectations file disables the story on the rendering benchmark, which rendering_representative_perf_tests are part of.
+So please add the a bug for each skipped test and link to `Internals>GPU>Metrics`.
+
+If the test is part of representative perf tests on Windows or MacOS, this
+should be done under rendering.desktop benchmark and if it's a test on Android
+under rendering.mobile.
\ No newline at end of file