The following revision refers to this bug:
  https://chromium.googlesource.com/infra/infra/+/ad39d4b4ddd7bccca398f14f252bf3917a87cc18

commit ad39d4b4ddd7bccca398f14f252bf3917a87cc18
Author: Sharu Jiang <katesonia@google.com>
Date: Mon Aug 21 23:48:07 2017

[Predator] Change CracasParser to parse a list of stacktrace strings.

Cracas will send a list of callstack strings instead of one string, change predator accordingly.
So Cracas and Fracas are no longer the same, we should separate them from ChromeCashData and ChromeCrashParser.

Bug:  749308 
Change-Id: If08cb1d80205bbff2ce9848ec250e88bc7c77a6b
Reviewed-on: https://chromium-review.googlesource.com/597316
Commit-Queue: Sharu Jiang <katesonia@chromium.org>
Reviewed-by: Shuotao Gao <stgao@chromium.org>

[modify] https://crrev.com/ad39d4b4ddd7bccca398f14f252bf3917a87cc18/appengine/predator/app/common/model/test/chrome_crash_analysis_test.py
[modify] https://crrev.com/ad39d4b4ddd7bccca398f14f252bf3917a87cc18/appengine/predator/scripts/run_predator.py
[modify] https://crrev.com/ad39d4b4ddd7bccca398f14f252bf3917a87cc18/appengine/predator/app/common/model/cracas_crash_analysis.py
[modify] https://crrev.com/ad39d4b4ddd7bccca398f14f252bf3917a87cc18/appengine/predator/analysis/test/chrome_crash_data_test.py
[modify] https://crrev.com/ad39d4b4ddd7bccca398f14f252bf3917a87cc18/appengine/predator/analysis/test/chromecrash_parser_test.py
[modify] https://crrev.com/ad39d4b4ddd7bccca398f14f252bf3917a87cc18/appengine/predator/analysis/chromecrash_parser.py
[modify] https://crrev.com/ad39d4b4ddd7bccca398f14f252bf3917a87cc18/appengine/predator/analysis/chrome_crash_data.py
[modify] https://crrev.com/ad39d4b4ddd7bccca398f14f252bf3917a87cc18/appengine/predator/app/common/test/predator_for_chromecrash_test.py
[modify] https://crrev.com/ad39d4b4ddd7bccca398f14f252bf3917a87cc18/appengine/predator/app/common/predator_for_chromecrash.py
[modify] https://crrev.com/ad39d4b4ddd7bccca398f14f252bf3917a87cc18/appengine/predator/analysis/crash_data.py
[modify] https://crrev.com/ad39d4b4ddd7bccca398f14f252bf3917a87cc18/appengine/predator/analysis/clusterfuzz_data.py

Assuming this is fixed based on the CL in c#1.