Failing tests:
- All/ScrollbarsTest.NativeScrollbarChangeToMobileByEmulator/0
- All/ScrollbarsTest.NativeScrollbarChangeToMobileByEmulator/1
- PaintLayerClipperTest.ControlClipSelect

webkit_unit_tests was disabled on the chromeos bot, but enabled by this change:
"Run the blink unit tests on the remaining main bots."
https://chromium-review.googlesource.com/c/chromium/src/+/829874

I'll disable these tests on the bot.

CL: https://chromium-review.googlesource.com/c/chromium/src/+/831005

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/156d2268eb16999d2d3ae1099580796a38ece5ce

commit 156d2268eb16999d2d3ae1099580796a38ece5ce
Author: Hiroki Nakagawa <nhiroki@chromium.org>
Date: Mon Dec 18 06:48:51 2017

Disable ScrollbarsTest.NativeScrollbarChangeToMobileByEmulator etc on the chromeos bot

These tests are faling on the bot.

Bug:  795645 
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
Change-Id: If49997081c2034fea813724281bb8bf6fc3d81d3
TBR: fmalita@chromium.org
Reviewed-on: https://chromium-review.googlesource.com/831005
Reviewed-by: Hiroki Nakagawa <nhiroki@chromium.org>
Commit-Queue: Hiroki Nakagawa <nhiroki@chromium.org>
Cr-Commit-Position: refs/heads/master@{#524659}
[modify] https://crrev.com/156d2268eb16999d2d3ae1099580796a38ece5ce/third_party/WebKit/Source/core/layout/ScrollbarsTest.cpp
[modify] https://crrev.com/156d2268eb16999d2d3ae1099580796a38ece5ce/third_party/WebKit/Source/core/paint/PaintLayerClipperTest.cpp

 Issue 797590  has been merged into this issue.

 Issue 795440  has been merged into this issue.

chaopeng could you take a look?

These tests failed because native theme will check Feature Overlay Scrollbar not RuntimeFeature Overlay Scrollbar. 

[11527:11527:0104/085630.624318:9737378073:FATAL:native_theme_aura.cc(178)] Check failed: !use_overlay_scrollbars_. 

Also we should cover CrOS, default enable AuraOverlayScrollbar then turn on MobileOverlayScrollbar for emulator.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/79236fa704043783daaa422e4e78666242738648

commit 79236fa704043783daaa422e4e78666242738648
Author: chaopeng <chaopeng@chromium.org>
Date: Mon Jan 08 17:12:46 2018

Fix NativeScrollbarChangeToMobileByEmulator on CrOS bots

NativeScrollbarChangeToMobileByEmulator failed on CrOS bots because Aura
Overlay Scrollbar enable by default on CrOS and NativeTheme will DCHECK
scrollbar theme. So we can not change to non Overlay Scrollbar and disable
mock theme.

In this CL, we change NativeScrollbarChangeToMobileByEmulator to
ScrollbarAppearanceTest and use StubWebThemeEngine which skip the
native theme check and cover overlay scrollbar and no overlay scrollbar as
default on all platform.

Bug:  795645 
Change-Id: Ic19b166817ee19ea90949e051fbc636b0a326ac2
Reviewed-on: https://chromium-review.googlesource.com/850933
Reviewed-by: David Bokan <bokan@chromium.org>
Commit-Queue: Jianpeng Chao <chaopeng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#527656}
[modify] https://crrev.com/79236fa704043783daaa422e4e78666242738648/third_party/WebKit/Source/core/layout/ScrollbarsTest.cpp

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/5d675f772503003ade32a3a0ac32a69c97a2384b

commit 5d675f772503003ade32a3a0ac32a69c97a2384b
Author: Hans Wennborg <hans@chromium.org>
Date: Wed May 23 10:14:17 2018

Android test exclusions: don't exclude webkit_unit_tests

These tests do pass on some bots, e.g. [1], and it's not clear why they
were being excluded. If there's a legitimate reason for them not to run
on Android, let's figure it out and get a bug filed.

Sheriffs: if this causes the tests to start failing on Android bots,
please file a bug with information about the error, put the exclusion
back and reference the bug.

Disable ProtocolParserTest.Reading on Android until it's fixed,
see the third bug.

(The CrOS failure was fixed a few months ago, see  crbug.com/795645 )

Bug:  842698 ,  795645 ,  845816 

 [1] https://ci.chromium.org/buildbot/chromium.clang/ToTAndroid/3343

R=thakis@chromium.org

Change-Id: I4c683170508d431864880774543f942cf7446b88
Reviewed-on: https://chromium-review.googlesource.com/1068873
Commit-Queue: Hans Wennborg <hans@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#561021}
[modify] https://crrev.com/5d675f772503003ade32a3a0ac32a69c97a2384b/testing/buildbot/chromium.android.fyi.json
[modify] https://crrev.com/5d675f772503003ade32a3a0ac32a69c97a2384b/testing/buildbot/chromium.android.json
[modify] https://crrev.com/5d675f772503003ade32a3a0ac32a69c97a2384b/testing/buildbot/chromium.chromiumos.json
[modify] https://crrev.com/5d675f772503003ade32a3a0ac32a69c97a2384b/testing/buildbot/test_suite_exceptions.pyl
[modify] https://crrev.com/5d675f772503003ade32a3a0ac32a69c97a2384b/third_party/blink/renderer/core/inspector/protocol_parser_test.cc