Add CFX_ByteStringC::CharAt() to avoid c_str() and casts

Add CFX_ByteStringC::CharAt() to avoid c_str() and casts.

Most of the time, we want to operate on chars as if they
were unsigned, but there are a few places where we need
the default (questionably signed) values. Consolidate
the casting in a single place rather than forcing callers
to get a char* ptr.

BUG=pdfium:493
Committed: https://pdfium.googlesource.com/pdfium/+/28c7844c1ef5ea0c8727b890e9ff56b593119a00

[Tom Sepez, 2016-05-12 18:54:11]

Description was changed from

==========
Add CFX_ByteStringC::CharAt() to avoid casts

Most of the time, we want to operate on chars as if they
were unsigned, but there are a few places where we need
the default (questionably signed) values. Consolidate
the casting in a single place.

BUG=
==========

to

==========
Add CFX_ByteStringC::CharAt() to avoid c_str() and casts.

Most of the time, we want to operate on chars as if they
were unsigned, but there are a few places where we need
the default (questionably signed) values. Consolidate
the casting in a single place rather than forcing callers
to get a char* ptr.

BUG=493
==========

[Tom Sepez, 2016-05-12 18:54:12]

tsepez@chromium.org changed reviewers:
+ thestig@chromium.org

[Tom Sepez, 2016-05-12 18:54:22]

Lei, for review.

[Lei Zhang, 2016-05-12 22:36:02]

Description was changed from

==========
Add CFX_ByteStringC::CharAt() to avoid c_str() and casts.

Most of the time, we want to operate on chars as if they
were unsigned, but there are a few places where we need
the default (questionably signed) values. Consolidate
the casting in a single place rather than forcing callers
to get a char* ptr.

BUG=493
==========

to

==========
Add CFX_ByteStringC::CharAt() to avoid c_str() and casts.

Most of the time, we want to operate on chars as if they
were unsigned, but there are a few places where we need
the default (questionably signed) values. Consolidate
the casting in a single place rather than forcing callers
to get a char* ptr.

BUG=pdfium:493
==========

[Lei Zhang, 2016-05-12 22:47:26]

lgtm

I changed the BUG= line so it doesn't point to an ancient Chromium bug.

[Tom Sepez, 2016-05-12 22:51:57]

The CQ bit was checked by tsepez@chromium.org

[commit-bot: I haz the power, 2016-05-12 22:52:02]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1972053003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1972053003/1

[commit-bot: I haz the power, 2016-05-12 22:52:17]

Description was changed from

==========
Add CFX_ByteStringC::CharAt() to avoid c_str() and casts.

Most of the time, we want to operate on chars as if they
were unsigned, but there are a few places where we need
the default (questionably signed) values. Consolidate
the casting in a single place rather than forcing callers
to get a char* ptr.

BUG=pdfium:493
==========

to

==========
Add CFX_ByteStringC::CharAt() to avoid c_str() and casts.

Most of the time, we want to operate on chars as if they
were unsigned, but there are a few places where we need
the default (questionably signed) values. Consolidate
the casting in a single place rather than forcing callers
to get a char* ptr.

BUG=pdfium:493

Committed:
https://pdfium.googlesource.com/pdfium/+/28c7844c1ef5ea0c8727b890e9ff56b59311...
==========

[commit-bot: I haz the power, 2016-05-12 22:52:18]

Committed patchset #1 (id:1) as
https://pdfium.googlesource.com/pdfium/+/28c7844c1ef5ea0c8727b890e9ff56b59311...