The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/e4c83d8a956c7ca4369c814802e8f2adafee7906

commit e4c83d8a956c7ca4369c814802e8f2adafee7906
Author: Tanmoy Mollik <triploblastic@google.com>
Date: Mon Jan 21 11:32:04 2019

Implement OnMemoryDump() for css_style_sheet_resource

Implemented the OnMemoryDump() function for css_style_sheet_resource so
that the memory dump from css sheets can be seen in tracing.

Bug: 923023
Change-Id: I4b386f4469da60a88972bbbe66f56367df8e9264
Reviewed-on: https://chromium-review.googlesource.com/c/1417591
Reviewed-by: Benoit L <lizeb@chromium.org>
Reviewed-by: Nate Chapin <japhet@chromium.org>
Commit-Queue: Tanmoy Mollik <triploblastic@google.com>
Cr-Commit-Position: refs/heads/master@{#624556}
[modify] https://crrev.com/e4c83d8a956c7ca4369c814802e8f2adafee7906/third_party/blink/renderer/core/loader/resource/css_style_sheet_resource.cc
[modify] https://crrev.com/e4c83d8a956c7ca4369c814802e8f2adafee7906/third_party/blink/renderer/core/loader/resource/css_style_sheet_resource.h

let's make it a [meta] bug: attaching a few dependent issues.

Went through the call hierarchy of css_style_sheet_resource and it seems like there is no hidden resource that is unaccounted for. Did a local test on machine by creating a server with a large css file and it seems that was loaded. Sometimes when trying to find dumps for this resource on various websites it may not appear in memory tracing. Maybe some of those websites were not css heavy websites.