The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/0b0376dce2839aee9b240fc8eb7e6b05e1f48b05

commit 0b0376dce2839aee9b240fc8eb7e6b05e1f48b05
Author: Xida Chen <xidachen@chromium.org>
Date: Mon Apr 23 14:01:08 2018

Mark scroll-position-restored-on-back-at-load-event.html flaky on Leak bot

TBR=clamy@chromium.org
NOTRY=true

Bug:  835802 
Change-Id: Ib93a0351c6fbae9ed7998679c01334abe20ee256
Reviewed-on: https://chromium-review.googlesource.com/1023792
Commit-Queue: Xida Chen <xidachen@chromium.org>
Reviewed-by: Xida Chen <xidachen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#552684}
[modify] https://crrev.com/0b0376dce2839aee9b240fc8eb7e6b05e1f48b05/third_party/WebKit/LayoutTests/LeakExpectations

Hmm, looks like this test is leaking memory. 

I can reproduce this test locally. But I don't know how can the back.html leak, it only has 1 line `<script>history.back()</script>`.

Log:

```
There are 1 documents currently alive:
- Document 0x5970bea9858 URL: file:///usr/local/google/home/chaopeng/workspace/chromium/src/third_party/WebKit/LayoutTests/resources/back.html
#LEAK - renderer pid 228904 ({"numberOfLiveNodes":[4,6]})
#EOF
[228875:228882:0426/110745.356951:WARNING:discardable_shared_memory_manager.cc(431)] Some MojoDiscardableSharedMemoryManagerImpls are still alive. They will be leaked.
```

It sounds like an issue with cleaning up the old document but I don't have a good sense of these kind of lifetime issues. +dcheng@ is the expert here, any tips on where to look or how to fix this?

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/207e86621d28ddc206c333bdd12921ccdda12c7f

commit 207e86621d28ddc206c333bdd12921ccdda12c7f
Author: chaopeng <chaopeng@chromium.org>
Date: Thu May 31 23:08:04 2018

Convert scroll-position-restored-on-back-at-load-event.html to new style

It can fix the leak by convert test to new style.

Bug:  835802 
Change-Id: Icb8efd927fc0e8fc8301be6b7c1c0efd9ed51504
Reviewed-on: https://chromium-review.googlesource.com/1028835
Reviewed-by: David Bokan <bokan@chromium.org>
Commit-Queue: Jianpeng Chao <chaopeng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#563421}
[delete] https://crrev.com/329c2a2fdedbcbb7990413100d4e59f57e53d8a4/third_party/WebKit/LayoutTests/fast/loader/scroll-position-restored-on-back-at-load-event-expected.txt
[modify] https://crrev.com/207e86621d28ddc206c333bdd12921ccdda12c7f/third_party/WebKit/LayoutTests/fast/loader/scroll-position-restored-on-back-at-load-event.html

Bot looks good! https://test-results.appspot.com/dashboards/flakiness_dashboard.html#testType=webkit_layout_tests&tests=scroll-position-restored-on-back-at-load-event.html

As for why...¯\_(ツ)_/¯

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/274c88095427a82e98262b93912aac48bb0f4e4f

commit 274c88095427a82e98262b93912aac48bb0f4e4f
Author: chaopeng <chaopeng@chromium.org>
Date: Thu Jun 07 16:56:34 2018

Remove scroll-position-restored-on-back-at-load-event in LeakExpectation

scroll-position-restored-on-back-at-load-event was fixed in
crrev.com/c/207e86621d28ddc206c333bdd12921ccdda12c7f.

Bug:  835802 
Change-Id: Ic69c2844799d8aa7e2c57c4f952c36fd986b6cee
Reviewed-on: https://chromium-review.googlesource.com/1089588
Reviewed-by: David Bokan <bokan@chromium.org>
Commit-Queue: Jianpeng Chao <chaopeng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#565299}
[modify] https://crrev.com/274c88095427a82e98262b93912aac48bb0f4e4f/third_party/WebKit/LayoutTests/LeakExpectations