Fix generic font family issue on Android

Fix generic font family issue on Android

- standard font family should go Android path on Android;
- for non-generic font families, familyNameFromSettings should return
  an empty AtomicString.

BUG=347121
TEST=platform/android/fast/text/international/non-generic-font-fallback.html
R=dglazkov@chromium.org

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=168173

[dglazkov, 2014-02-28 21:30:29]

https://codereview.chromium.org/184703003/diff/20001/Source/core/css/CSSFontS...
File Source/core/css/CSSFontSelector.cpp (right):

https://codereview.chromium.org/184703003/diff/20001/Source/core/css/CSSFontS...
Source/core/css/CSSFontSelector.cpp:161: return
FontCache::getGenericFamilyNameForScript(FontFamilyNames::webkit_standard,
script);
This is okay, but can we not instead unfork this codepath? Effectively,
getGenericFamilyNameForScript does the same thing as
FontCache::getFontFamilyForCharacter, and we shouldn't need to call it here?

[Xianzhu, 2014-02-28 22:15:12]

https://codereview.chromium.org/184703003/diff/20001/Source/core/css/CSSFontS...
File Source/core/css/CSSFontSelector.cpp (right):

https://codereview.chromium.org/184703003/diff/20001/Source/core/css/CSSFontS...
Source/core/css/CSSFontSelector.cpp:161: return
FontCache::getGenericFamilyNameForScript(FontFamilyNames::webkit_standard,
script);
On 2014/02/28 21:30:30, Dimitri Glazkov wrote:
> This is okay, but can we not instead unfork this codepath? Effectively,
> getGenericFamilyNameForScript does the same thing as
> FontCache::getFontFamilyForCharacter, and we shouldn't need to call it here?

FontCache::getFontFamilyForCharacter doesn't actually work for multiple locales,
because we don't have separated entries for different locales in a single glyph
tree. To make it work we need an additional field m_locale in FontDescription
and FontData, so that we can distinguish different locales of them. I tried this
method several months ago in https://codereview.chromium.org/23503080/, but
finally chose https://codereview.chromium.org/24622002/ because of the
complexity and uncertainty about memory and performance of the former.

Actually we have already distinguished locales at the top level if different
locales has different font families for generic font families. This seems more
efficient than distinguish locales at each GlyphPageTreeNode. For now we require
glyphs in one glyph tree are for the same locale. Breaking this causes bugs,
like this one, and crbug.com/348078.

The forked codepath for Android is to meet the above requirement.

I think crbug.com/348078 can also be resolved with the similar method.

[dglazkov, 2014-02-28 22:19:47]

I see, lgtm.

[Xianzhu, 2014-02-28 22:31:40]

The CQ bit was checked by wangxianzhu@chromium.org

[commit-bot: I haz the power, 2014-02-28 22:31:46]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/wangxianzhu@chromium.org/184703003/20001

[commit-bot: I haz the power, 2014-03-01 00:02:23]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-03-01 00:02:24]

Retried try job too often on blink_android_compile_dbg for step(s) webkit_lint
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=blink_andr...

[Xianzhu, 2014-03-01 00:03:37]

The CQ bit was checked by wangxianzhu@chromium.org

[commit-bot: I haz the power, 2014-03-01 00:03:50]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/wangxianzhu@chromium.org/184703003/20001

[Xianzhu, 2014-03-01 00:43:01]

Committed patchset #1 manually as r168173 (presubmit successful).