i will take this issue.

https://chromium-review.googlesource.com/c/chromium/src/+/1055029 seems ready to be submitted.
Could somebody help me submit this patch to the CQ since I don't have try job access? 
Also, I can't edit the bug as fixed or closed.

I submitted for you, should be landing soon

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/311cb1b4bd88be4517d3734f117a0b74edd1bd7c

commit 311cb1b4bd88be4517d3734f117a0b74edd1bd7c
Author: Euisang Lim <eui-sang.lim@samsung.com>
Date: Fri May 18 14:57:40 2018

[WebUI] Change the background color for Web UI pages

Change the background color for Web UI pages(Settings, Extensions,
History, Bookmarks, Downloads) from #F1F1F1 to #F8F9FA(GG50)
for MD Refresh.

Change the background-color of each files of Settings, Extensions,
and Downloads.

Change --md-background-color in ui/webui for History and Bookmarks
which use var(--md-background-color).

Bug:  841839 
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: Ib6eeb53f38e385f1de617e5eaba83e8325d7119a
Reviewed-on: https://chromium-review.googlesource.com/1055029
Reviewed-by: Bernhard Bauer <bauerb@chromium.org>
Reviewed-by: Scott Chen <scottchen@chromium.org>
Commit-Queue: Bernhard Bauer <bauerb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#559893}
[modify] https://crrev.com/311cb1b4bd88be4517d3734f117a0b74edd1bd7c/chrome/browser/resources/md_downloads/downloads.html
[modify] https://crrev.com/311cb1b4bd88be4517d3734f117a0b74edd1bd7c/chrome/browser/resources/md_extensions/extensions.html
[modify] https://crrev.com/311cb1b4bd88be4517d3734f117a0b74edd1bd7c/chrome/browser/resources/settings/settings.html
[modify] https://crrev.com/311cb1b4bd88be4517d3734f117a0b74edd1bd7c/ui/webui/resources/css/md_colors.css

Could you please let us know the exact steps to verify this issue from TE End & what are all the flags to be enabled to check this issue.

 Tried to launch chrome with --md-background-color flag but no difference in background color observed in chrome UI pages (chrome://settings,chrome://Bookmarks,chrome://history & chrome://extensions on Canary-	68.0.3436.0.

Thanks..!

It doesn't seem like the change is on canary yet, pleaes wait another day or two to verify.

>  Tried to launch chrome with --md-background-color flag but no difference in background color observed in chrome UI pages 

Also note that there is no --md-background-color flag. That's not the right way to try to verify this change.