Add effective size vs. size explanation to docs

Add effective size vs. size explanation to docs

BUG=chromium:663353
Review-Url: https://codereview.chromium.org/2621993004
Cr-Commit-Position: refs/heads/master@{#442917}
Committed: https://chromium.googlesource.com/chromium/src/+/9dddc3fac1b1033d6ae85cad37a15c831fe7c156

[hjd, 2017-01-11 15:38:44]

hjd@chromium.org changed reviewers:
+ perezju@chromium.org, primiano@chromium.org

[hjd, 2017-01-11 15:38:45]

ptal, thanks

[perezju, 2017-01-11 15:58:50]

lgtm, nice and easy to read :)

[hjd, 2017-01-11 16:04:57]

The CQ bit was checked by hjd@chromium.org

[commit-bot: I haz the power, 2017-01-11 16:05:17]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-01-11 16:16:41]

CQ is committing da patch.

Bot data: {"patchset_id": 20001, "attempt_start_ts": 1484150697502180,
"parent_rev": "4260025dd80eed380e0c1fff0e4be2bdd0ae0e8a", "commit_rev":
"9dddc3fac1b1033d6ae85cad37a15c831fe7c156"}

[commit-bot: I haz the power, 2017-01-11 16:17:11]

Description was changed from

==========
Add effective size vs. size explanation to docs

BUG=chromium:663353
==========

to

==========
Add effective size vs. size explanation to docs

BUG=chromium:663353

Review-Url: https://codereview.chromium.org/2621993004
Cr-Commit-Position: refs/heads/master@{#442917}
Committed:
https://chromium.googlesource.com/chromium/src/+/9dddc3fac1b1033d6ae85cad37a1...
==========

[commit-bot: I haz the power, 2017-01-11 16:17:12]

Committed patchset #2 (id:20001) as
https://chromium.googlesource.com/chromium/src/+/9dddc3fac1b1033d6ae85cad37a1...