r541011 marked these tests as SLOW, but they are still timing out in Debug, MSAN and ASAN. I am adding the corresponding expectations in https://crrev.com/c/950903. 

Example Log Output:
9:51:49.177 2030 Retrying 1 unexpected failure, attempt 2 of 3...
19:51:49.177 2030 Sharding tests ...
19:51:49.177 2030 Starting 1 worker ...
19:51:49.178 2030 worker/0 starting
19:57:29.501 2030 killed pid 21578
19:57:29.503 2030 worker/0 http/tests/media/media-src-suspend-before-have-metadata.html output stderr lines:
19:57:29.503 2030   
19:57:29.503 2030   DevTools listening on ws://127.0.0.1:43398/devtools/browser/65e80b1b-e4d7-4bf2-9f6d-b25ee0aa0441
19:57:29.503 2030   Fontconfig warning: "/etc/fonts/fonts.conf", line 146: blank doesn't take any effect anymore. please remove it from your fonts.conf
19:57:29.503 2030   ALSA lib confmisc.c:768:(parse_card) cannot find card '0'
19:57:29.503 2030   ALSA lib conf.c:4248:(_snd_config_evaluate) function snd_func_card_driver returned error: No such file or directory
19:57:29.503 2030   ALSA lib confmisc.c:392:(snd_func_concat) error evaluating strings
19:57:29.503 2030   ALSA lib conf.c:4248:(_snd_config_evaluate) function snd_func_concat returned error: No such file or directory
19:57:29.503 2030   ALSA lib confmisc.c:1251:(snd_func_refer) error evaluating name
19:57:29.503 2030   ALSA lib conf.c:4248:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
19:57:29.503 2030   ALSA lib conf.c:4727:(snd_config_expand) Evaluate error: No such file or directory
19:57:29.503 2030   ALSA lib pcm.c:2239:(snd_pcm_open_noupdate) Unknown PCM default
19:57:29.503 2030   [21578:21613:0305/195205.821288:WARNING:alsa_util.cc(24)] PcmOpen: default,No such file or directory
19:57:29.503 2030   ALSA lib confmisc.c:768:(parse_card) cannot find card '0'
19:57:29.503 2030   ALSA lib conf.c:4248:(_snd_config_evaluate) function snd_func_card_driver returned error: No such file or directory
19:57:29.503 2030   ALSA lib confmisc.c:392:(snd_func_concat) error evaluating strings
19:57:29.503 2030   ALSA lib conf.c:4248:(_snd_config_evaluate) function snd_func_concat returned error: No such file or directory
19:57:29.503 2030   ALSA lib confmisc.c:1251:(snd_func_refer) error evaluating name
19:57:29.503 2030   ALSA lib conf.c:4248:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
19:57:29.503 2030   ALSA lib conf.c:4727:(snd_config_expand) Evaluate error: No such file or directory
19:57:29.503 2030   ALSA lib pcm.c:2239:(snd_pcm_open_noupdate) Unknown PCM default
19:57:29.504 2030   [21578:21613:0305/195205.821878:WARNING:alsa_util.cc(24)] PcmOpen: plug:default,No such file or directory
19:57:29.504 2030   [1:17:0305/195205.824429:ERROR:render_media_log.cc(30)] MediaEvent: MEDIA_ERROR_LOG_ENTRY {"error":"Failed to reconcile encoded audio times with decoded output."}
19:57:29.504 2030 [1/1] http/tests/media/media-src-suspend-before-have-metadata.html failed unexpectedly (test timed out)
19:57:29.504 2030 worker/0 killing primary driver
19:57:29.505 2030 worker/0 killing secondary driver
19:57:29.505 2030 worker/0 http/tests/media/media-src-suspend-before-have-metadata.html failed:
19:57:29.505 2030 worker/0  test timed out
19:57:29.505 2030 worker/0 killing secondary driver
19:57:29.505 2030 worker/0 exiting
19:57:29.505 2030 worker/0 cleaning up
19:57:29.505 2030 worker/0 killing primary driver
19:57:29.505 2030 worker/0 killing secondary driver

20:03:14.829 2030 Tests that timed out or crashed:
20:03:14.829 2030   http/tests/media/media-src-suspend-before-have-metadata.html took 330.1 seconds


dalecurtis@, could you take a look at this?

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/be387db7ec4528fbe80a7167611b8e1067611ee0

commit be387db7ec4528fbe80a7167611b8e1067611ee0
Author: jdoerrie <jdoerrie@chromium.org>
Date: Tue Mar 06 13:51:52 2018

[webkit] Add Expectations for very SLOW tests on Linux

TBR=dalecurtis@chromium.org

Bug:  819194 
Change-Id: I48b31af67509bad80363e37284cb4d0e3a667ee7
Reviewed-on: https://chromium-review.googlesource.com/950903
Reviewed-by: Jan Wilken Dörrie <jdoerrie@chromium.org>
Commit-Queue: Jan Wilken Dörrie <jdoerrie@chromium.org>
Cr-Commit-Position: refs/heads/master@{#541094}
[modify] https://crrev.com/be387db7ec4528fbe80a7167611b8e1067611ee0/third_party/WebKit/LayoutTests/ASANExpectations
[modify] https://crrev.com/be387db7ec4528fbe80a7167611b8e1067611ee0/third_party/WebKit/LayoutTests/MSANExpectations
[modify] https://crrev.com/be387db7ec4528fbe80a7167611b8e1067611ee0/third_party/WebKit/LayoutTests/TestExpectations

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/6438cf1ff7f9e249d150b5dc22d0157193c09cac

commit 6438cf1ff7f9e249d150b5dc22d0157193c09cac
Author: Dale Curtis <dalecurtis@chromium.org>
Date: Thu Mar 29 02:34:01 2018

Simplify suspend/resume testing by having WMP suspend based on state.

This removes the need for stalled loading to force states on the WMPI
pipeline by instead having WMPI suspend once it reaches one of the
target states.

This provides equivalent coverage with much faster testing.

BUG= 819194 , 817705 , 756897 
TEST=no more flaky tests.

Change-Id: I1fa9e1ff6d165ed7921abf62127d3c2cd89f5707
Reviewed-on: https://chromium-review.googlesource.com/980802
Reviewed-by: Mounir Lamouri <mlamouri@chromium.org>
Reviewed-by: Pavel Feldman <pfeldman@chromium.org>
Commit-Queue: Dale Curtis <dalecurtis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#546704}
[modify] https://crrev.com/6438cf1ff7f9e249d150b5dc22d0157193c09cac/media/blink/webmediaplayer_impl.cc
[modify] https://crrev.com/6438cf1ff7f9e249d150b5dc22d0157193c09cac/media/blink/webmediaplayer_impl.h
[modify] https://crrev.com/6438cf1ff7f9e249d150b5dc22d0157193c09cac/third_party/WebKit/LayoutTests/ASANExpectations
[modify] https://crrev.com/6438cf1ff7f9e249d150b5dc22d0157193c09cac/third_party/WebKit/LayoutTests/MSANExpectations
[modify] https://crrev.com/6438cf1ff7f9e249d150b5dc22d0157193c09cac/third_party/WebKit/LayoutTests/SlowTests
[modify] https://crrev.com/6438cf1ff7f9e249d150b5dc22d0157193c09cac/third_party/WebKit/LayoutTests/TestExpectations
[delete] https://crrev.com/dae40d733338a3c54add2a9385674e9094cd04bb/third_party/WebKit/LayoutTests/http/tests/media/media-src-suspend-after-have-future-data.html
[delete] https://crrev.com/dae40d733338a3c54add2a9385674e9094cd04bb/third_party/WebKit/LayoutTests/http/tests/media/media-src-suspend-after-have-metadata.html
[delete] https://crrev.com/dae40d733338a3c54add2a9385674e9094cd04bb/third_party/WebKit/LayoutTests/http/tests/media/media-src-suspend-before-have-metadata.html
[modify] https://crrev.com/6438cf1ff7f9e249d150b5dc22d0157193c09cac/third_party/WebKit/LayoutTests/media/media-src-suspend-after-have-enough-data.html
[add] https://crrev.com/6438cf1ff7f9e249d150b5dc22d0157193c09cac/third_party/WebKit/LayoutTests/media/media-src-suspend-after-have-future-data.html
[add] https://crrev.com/6438cf1ff7f9e249d150b5dc22d0157193c09cac/third_party/WebKit/LayoutTests/media/media-src-suspend-after-have-metadata.html
[add] https://crrev.com/6438cf1ff7f9e249d150b5dc22d0157193c09cac/third_party/WebKit/LayoutTests/media/media-src-suspend-before-have-metadata.html
[modify] https://crrev.com/6438cf1ff7f9e249d150b5dc22d0157193c09cac/third_party/WebKit/LayoutTests/media/suspend-util.js
[modify] https://crrev.com/6438cf1ff7f9e249d150b5dc22d0157193c09cac/third_party/WebKit/Source/core/testing/Internals.cpp
[modify] https://crrev.com/6438cf1ff7f9e249d150b5dc22d0157193c09cac/third_party/WebKit/Source/core/testing/Internals.h
[modify] https://crrev.com/6438cf1ff7f9e249d150b5dc22d0157193c09cac/third_party/WebKit/Source/core/testing/Internals.idl
[modify] https://crrev.com/6438cf1ff7f9e249d150b5dc22d0157193c09cac/third_party/WebKit/public/platform/WebMediaPlayer.h