Make members of SegmentedSubstring private

Make members of SegmentedSubstring private

Before this CL, SegmentedSubstring::{m_length,m_data} was declared public.
This CL makes them private and adds public accessors to them.

BUG=None
TESTS=Refactoring only. Shouldn't change any behaviour.

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=201221

[kouhei (in TOK), 2015-08-26 09:24:46]

kouhei@chromium.org changed reviewers:
+ haraken@chromium.org

[kouhei (in TOK), 2015-08-26 09:25:43]

The CQ bit was checked by kouhei@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-08-26 09:25:50]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1317693006/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1317693006/20001

[haraken, 2015-08-26 09:34:20]

LGTM

[commit-bot: I haz the power, 2015-08-26 10:38:30]

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

[commit-bot: I haz the power, 2015-08-26 10:38:31]

Dry run: This issue passed the CQ dry run.

[kouhei (in TOK), 2015-08-26 11:00:42]

The CQ bit was checked by kouhei@chromium.org

[commit-bot: I haz the power, 2015-08-26 11:00:52]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1317693006/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1317693006/20001

[commit-bot: I haz the power, 2015-08-26 11:05:16]

Committed patchset #2 (id:20001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=201221