commit 3857f5dccf0f16288947c8c3c79b2a9a5bbd72b5
author Manish Jethani <m.jethani@eyeo.com> Wed Nov 01 16:46:46 2017
committer Commit Bot <commit-bot@chromium.org> Wed Nov 01 16:46:46 2017
tree 4fc7d7db39c525240e1f4f272abad2b0078b2af0
parent ae69109e899d4b89e3382f427db664c2180e974e

Support @font-face rules in user style sheets

@font-face rules in author style sheets are passed back to StyleEngine
via ScopedStyleResolver. With crrev.com/c/641294 we started treating
style sheets injected by extensions as user style sheets instead. Since
user style sheets apply to all scopes, they never go via
ScopedStyleResolver but are rather managed by StyleEngine directly.

crrev.com/c/641294 broke extensions using custom fonts because
StyleEngine fails to account for @font-face rules in user style sheets.

Fonts from both user and author style sheets must be maintained in the
same font cache. Even though style sheets can be added in any order,
@font-face rules in author style sheets must appear after those in user
style sheets. In order to achieve this result efficiently, we use a
"dirty" flag and refresh the font cache only once per cycle.

StyleEngine::ApplyRuleSetChanges may be called twice, once for user
style sheets (all scopes) and once for author style sheets (document
scope). If fonts have changed in user style sheets, we simply set the
dirty flag. If fonts have changed in author style sheets, we set the
dirty flag but also then refresh the font cache by first adding all the
@font-face rules from the active user style sheets and then re-adding
all the new author style sheets. This ensures that the font cache is
refreshed only once while the fonts are added in the correct order.

BUG=632009,779048

Change-Id: I58c1070af3ecae925e4afb91cbbb7cb00ee187fd
Reviewed-on: https://chromium-review.googlesource.com/743642
Commit-Queue: nainar <nainar@chromium.org>
Reviewed-by: nainar <nainar@chromium.org>
Cr-Commit-Position: refs/heads/master@{#513154}