Document SkString::resize(int) as destructive.

Document SkString::resize(int) as destructive.

It is easy to think in some cases that SkString::resize(int) is not
destructive, since optimizations mean that most of the time the data
is still there after a resize. However, in the general case, the
original string's data is lost and the new SkString contains garbage.

Committed: https://skia.googlesource.com/skia/+/b2885d59bccb1c5045e52135c5dd7a85a57694fa

[bungeman-skia, 2015-08-31 15:33:03]

bungeman@google.com changed reviewers:
+ caryclark@google.com, reed@google.com

[bungeman-skia, 2015-08-31 15:33:04]

This recently came up (see https://codereview.chromium.org/1317913005/#ps60001 )
and it seems non-trivial to change. Most users appear to simply be resizing and
then using writable_string to set the content, which appears to be what this was
originally designed to do. However, there are a few users which are relying on
the underlying data to remain the same after strictly shortening the string.
Maybe these should create a new string, or use SkString::remove(size_t, size_t)?

[bungeman-skia, 2015-08-31 16:03:58]

The CQ bit was checked by bungeman@google.com to run a CQ dry run

[commit-bot: I haz the power, 2015-08-31 16:04:05]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1304833004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1304833004/1

[commit-bot: I haz the power, 2015-08-31 16:09:07]

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

[commit-bot: I haz the power, 2015-08-31 16:09:08]

Dry run: This issue passed the CQ dry run.

[reed1, 2015-08-31 21:07:10]

lgtm

[bungeman-skia, 2015-08-31 21:35:57]

The CQ bit was checked by bungeman@google.com

[commit-bot: I haz the power, 2015-08-31 21:36:13]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1304833004/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1304833004/1

[commit-bot: I haz the power, 2015-08-31 21:36:52]

Committed patchset #1 (id:1) as
https://skia.googlesource.com/skia/+/b2885d59bccb1c5045e52135c5dd7a85a57694fa