commit 36c08c1fb50c18303e82236c4bf143bbaf9c675b
author Koji Ishii <kojii@chromium.org> Tue Nov 20 13:33:18 2018
committer Commit Bot <commit-bot@chromium.org> Tue Nov 20 13:33:18 2018
tree 2ce198998fedc6373b935e17b0816bf02d1c4cc7
parent 478a17a5364bb91e3a3e0e54127f163ae4426605

Reland "Normalize Katakana to Hiragana in ScriptRunIterator"

This is a reland of 05672d8d19afbbfada4f027ac1a9f27228bc78a6

The original change was reverted as suspected to cause
Android CFI builder to fail:

[ RUN      ] RenderViewImplTest.PreferredSizeZoomed
[FATAL:data_pack.cc(444)] Check failed: !handle->HasResource(resource_id). Duplicate resource 25400 with scale 1

I cannot find any relationship to the failure, and
android_cfi_rel_ng trybot passes. Relanding to see if this
was really the cause.

Original change's description:
> Normalize Katakana to Hiragana in ScriptRunIterator
>
> This patch normalizes Katakana to Hiragana in ScriptData, and
> thus in ScriptRunIterator.
>
> There are 3 ICU script code for kana; USCRIPT_HIRAGANA,
> USCRIPT_KATAKANA, and USCRIPT_KATAKANA_OR_HIRAGANA. However,
> OpenType has only one 'kana' for all these 3 script codes.
>
> When shaping, HarfBuzz handles the normalization. However,
> Blink splits the incoming string by the ICU scripts.
> Splitting these 3 scripts is not useful but consumes CPU
> and memory.
>
> By normalizing in ScriptRunIterator, all types of Kana are
> in single run.
>
> timeToFirstContentfulPaint:layout shows ~3% improvements
> https://pinpoint-dot-chromeperf.appspot.com/job/10d9760fe40000
>
> though bink_perf.layout does not show much differences
> https://pinpoint-dot-chromeperf.appspot.com/job/14f19c00140000
>
> This is probably because Katakana characters are not used
> much in `japanese-kokoro-insert` (written in ~100 years ago,)
> while they are more used in modern pages.
>
> Bug: 636993
> Change-Id: If692bb575f2232b8fca10cd2ea87e3022debdf05
> Reviewed-on: https://chromium-review.googlesource.com/c/1337650
> Commit-Queue: Koji Ishii <kojii@chromium.org>
> Reviewed-by: Dominik Röttsches <drott@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#609119}

TBR=drott@chromium.org

Bug: 636993
Change-Id: I1d741fa47556c5e7bf47e3badcdcf60a81fbc22b
Reviewed-on: https://chromium-review.googlesource.com/c/1343583
Reviewed-by: Koji Ishii <kojii@chromium.org>
Commit-Queue: Koji Ishii <kojii@chromium.org>
Cr-Commit-Position: refs/heads/master@{#609680}