Chatted with Chan, and she pointed out that the mapping from step name to the isolate target name can be obtained from the step_metadata. Will look more into this later. And once this works, canonical_step_name in the step_metadata can be obtained for free, and then we can normalized step_name by directly using canonical_step_name, which should be more reliable.

canonical_step_name sgtm, but there will still be ash_unittests and mash_ash_unittests.

There are a few things that might be related: compile target name, isolate target name, test target name, GN label, ninja target name, binary name, etc.

The following revision refers to this bug:
  https://chromium.googlesource.com/infra/infra/+/3890a90dce70d1a083f4c25c7f3768294cbd27d9

commit 3890a90dce70d1a083f4c25c7f3768294cbd27d9
Author: Yuke Liao <liaoyuke@chromium.org>
Date: Fri Aug 10 18:37:56 2018

[Findit] Add function to get isolate_target_name

This is a pre-requirement CL for mapping different step names to the
same base test target that actually define the tests. For example:
viz_browser_tests -> browser_tests.
site_per_process_webkit_layout_tests -> webkit_layout_tests.

The utlimate solution is to add a base_test_target field in the GN
templates that defines the tests, but unfortunately, it doesn't exist
yet.

As of now, the closest thing we have is the isolate_target_name in the
step_metadata. Though there is a refactoring going on by Dirk that may
change the values of the isolate_target_name, I've synced with him and
he promised that he will make sure isolate_target_name stays the same
until the base_test_target is in place.

So, the conclusion is that it is safe to use isolate_target_name as a
temporary solution.

Bug:  848867 
Change-Id: I73f36c8a8ef7f3bcf0db3869bf0bc89076f2a421
Reviewed-on: https://chromium-review.googlesource.com/1171248
Commit-Queue: Yuke Liao <liaoyuke@chromium.org>
Reviewed-by: Jeffrey Li <lijeffrey@chromium.org>

[modify] https://crrev.com/3890a90dce70d1a083f4c25c7f3768294cbd27d9/appengine/findit/services/ci_failure.py
[modify] https://crrev.com/3890a90dce70d1a083f4c25c7f3768294cbd27d9/appengine/findit/services/test/ci_failure_test.py

The following revision refers to this bug:
  https://chromium.googlesource.com/infra/infra/+/0bb6ec645ac017ec5b06bdb12ef5cada2c685a5d

commit 0bb6ec645ac017ec5b06bdb12ef5cada2c685a5d
Author: Yuke Liao <liaoyuke@chromium.org>
Date: Fri Aug 10 21:56:08 2018

[FindIt] Add build number to flake detection model

In order to obtain step_metadata of a step, build number is required.
There are two options to get build numbers:
1. Query build bucket API using build id.
2. Query test-results table.

Both would work, but solution 2 is easier to implement and maintain.

Bug:  848867 
Change-Id: I558fd1d118c208c81c7696474e2750727195b5f4
Reviewed-on: https://chromium-review.googlesource.com/1171195
Commit-Queue: Yuke Liao <liaoyuke@chromium.org>
Reviewed-by: Jeffrey Li <lijeffrey@chromium.org>

[modify] https://crrev.com/0bb6ec645ac017ec5b06bdb12ef5cada2c685a5d/appengine/findit/model/flake/detection/test/flake_occurrence_test.py
[modify] https://crrev.com/0bb6ec645ac017ec5b06bdb12ef5cada2c685a5d/appengine/findit/services/flake_detection/flaky_tests.cq_false_rejection.sql
[modify] https://crrev.com/0bb6ec645ac017ec5b06bdb12ef5cada2c685a5d/appengine/findit/services/flake_detection/test/detect_cq_false_rejection_flakes_test.py
[modify] https://crrev.com/0bb6ec645ac017ec5b06bdb12ef5cada2c685a5d/appengine/findit/services/flake_detection/test/flake_report_util_test.py
[modify] https://crrev.com/0bb6ec645ac017ec5b06bdb12ef5cada2c685a5d/appengine/findit/model/flake/detection/flake_occurrence.py
[modify] https://crrev.com/0bb6ec645ac017ec5b06bdb12ef5cada2c685a5d/appengine/findit/services/flake_detection/detect_cq_false_rejection_flakes.py
[modify] https://crrev.com/0bb6ec645ac017ec5b06bdb12ef5cada2c685a5d/appengine/findit/handlers/flake/detection/test/show_flake_test.py

The following revision refers to this bug:
  https://chromium.googlesource.com/infra/infra/+/c0749177f9743c815350e3a2385997fb71b4ff54

commit c0749177f9743c815350e3a2385997fb71b4ff54
Author: Yuke Liao <liaoyuke@chromium.org>
Date: Mon Aug 13 17:00:06 2018

[Findit] Use isolate_target_name to normalize step names

This CL uses isolate_target_name to normalize step names so that
different steps that have the same base test targets are correctly
grouped together.

Bug:  848867 
Change-Id: Id0ebebec149533226ad6cb03c242bb40cb38450e
Reviewed-on: https://chromium-review.googlesource.com/1171785
Reviewed-by: Shuotao Gao <stgao@chromium.org>
Reviewed-by: Jeffrey Li <lijeffrey@chromium.org>
Commit-Queue: Yuke Liao <liaoyuke@chromium.org>

[modify] https://crrev.com/c0749177f9743c815350e3a2385997fb71b4ff54/appengine/findit/model/flake/detection/test/flake_occurrence_test.py
[modify] https://crrev.com/c0749177f9743c815350e3a2385997fb71b4ff54/appengine/findit/model/flake/detection/flake.py
[modify] https://crrev.com/c0749177f9743c815350e3a2385997fb71b4ff54/appengine/findit/services/flake_detection/test/detect_cq_false_rejection_flakes_test.py
[modify] https://crrev.com/c0749177f9743c815350e3a2385997fb71b4ff54/appengine/findit/model/flake/detection/test/flake_test.py
[modify] https://crrev.com/c0749177f9743c815350e3a2385997fb71b4ff54/appengine/findit/services/flake_detection/detect_cq_false_rejection_flakes.py
[modify] https://crrev.com/c0749177f9743c815350e3a2385997fb71b4ff54/appengine/findit/handlers/flake/detection/test/show_flake_test.py