The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/146eafbb2d1135f23696e2acca9a9c79cfa9b871

commit 146eafbb2d1135f23696e2acca9a9c79cfa9b871
Author: csharrison <csharrison@chromium.org>
Date: Tue Feb 14 17:40:33 2017

[LazyParseCSS] Add metrics for total # of rules at 0% and 100% usage

Metrics on Android were showing large % of sheets with 100% usage,
that we still lazily parse. This patch will help illuminate if this is an issue
in practice, by logging how much smaller these are than the average
sheet we lazily parse.

Ideally, these will be small enough that we won't need to add any gating
behavior and we can still lazily parse these, even if they don't need it.

BUG= 685623 

Review-Url: https://codereview.chromium.org/2687023003
Cr-Commit-Position: refs/heads/master@{#450397}

[modify] https://crrev.com/146eafbb2d1135f23696e2acca9a9c79cfa9b871/third_party/WebKit/Source/core/css/parser/CSSLazyParsingState.cpp
[modify] https://crrev.com/146eafbb2d1135f23696e2acca9a9c79cfa9b871/third_party/WebKit/Source/core/css/parser/CSSLazyParsingState.h
[modify] https://crrev.com/146eafbb2d1135f23696e2acca9a9c79cfa9b871/third_party/WebKit/Source/core/css/parser/CSSLazyParsingTest.cpp
[modify] https://crrev.com/146eafbb2d1135f23696e2acca9a9c79cfa9b871/third_party/WebKit/Source/core/css/parser/CSSParserImpl.cpp
[modify] https://crrev.com/146eafbb2d1135f23696e2acca9a9c79cfa9b871/tools/metrics/histograms/histograms.xml

Hi csharrison@, 

Is there an update to be had here? Thanks!

Yes I will tentatively mark this WontFix. I think the Dev data that I filed this bug for was just noisy. It does look like Android stylesheets use more rules, but only a bit more than desktop.