BlankText UMAs should be reported only for webfonts in block period

BlankText UMAs should be reported only for webfonts in block period

This fixes a bug where WebFont.HadBlankText and
WebFont.BlankTextShownTime are reported incorrectly when the webfont
falls back immediately, because of font-display:swap or the webfont
intervention.

BUG=591304
Review URL: https://codereview.chromium.org/1764913003

Cr-Commit-Position: refs/heads/master@{#379246}
(cherry picked from commit 802475025dd1465c1f6f99b114d9b9ac7a37e110)

Committed: https://chromium.googlesource.com/chromium/src/+/ad3c88f77d543f648f622980178fa453503d6c94

[Kunihiko Sakamoto, 2016-03-07 03:48:56]

Description was changed from

==========
BlankText UMAs should be reported only for webfonts in block period

This fixes a bug where WebFont.HadBlankText and
WebFont.BlankTextShownTime are reported incorrectly when the webfont
falls back immediately, because of font-display:swap or the webfont
intervention.

BUG=591304

Review URL: https://codereview.chromium.org/1764913003

Cr-Commit-Position: refs/heads/master@{#379246}
(cherry picked from commit 802475025dd1465c1f6f99b114d9b9ac7a37e110)
==========

to

==========
BlankText UMAs should be reported only for webfonts in block period

This fixes a bug where WebFont.HadBlankText and
WebFont.BlankTextShownTime are reported incorrectly when the webfont
falls back immediately, because of font-display:swap or the webfont
intervention.

BUG=591304

Review URL: https://codereview.chromium.org/1764913003

Cr-Commit-Position: refs/heads/master@{#379246}
(cherry picked from commit 802475025dd1465c1f6f99b114d9b9ac7a37e110)

Committed:
https://chromium.googlesource.com/chromium/src/+/ad3c88f77d543f648f622980178f...
==========

[Kunihiko Sakamoto, 2016-03-07 03:48:58]

Committed patchset #1 (id:1) manually as
ad3c88f77d543f648f622980178fa453503d6c94.