Improve early return in CGifLZWDecoder::Decode

Improve early return in CGifLZWDecoder::Decode

|code_size_cur| could be larger than |code_size|, so |code| could be
larger than |code_end|. If this happens, early return, since the Decode
has failed.

BUG=659417
Committed: https://pdfium.googlesource.com/pdfium/+/9be9c3486688b84c723f41c85327abec238f15f9

[npm, 2016-12-01 16:27:52]

Description was changed from

==========
Improve early return in CGifLZWDecoder::Decode

|code_size_cur| could be larger than |code_size|, so |code| could be
larger than |code_end|. If this happens, early return, since the Decode
has failed.

BUG=659417
==========

to

==========
Improve early return in CGifLZWDecoder::Decode

|code_size_cur| could be larger than |code_size|, so |code| could be
larger than |code_end|. If this happens, early return, since the Decode
has failed.

BUG=659417
==========

[npm, 2016-12-01 16:27:52]

npm@chromium.org changed reviewers:
+ tsepez@chromium.org, weili@chromium.org

[npm, 2016-12-01 16:27:58]

ptal

[Tom Sepez, 2016-12-01 17:56:40]

LGTM, I guess adding test would be hard?

[npm, 2016-12-01 18:06:09]

On 2016/12/01 17:56:40, Tom Sepez wrote:
> LGTM, I guess adding test would be hard?

I would need a PDF with gif. Or maybe we can start thinking about adding more
unittests like fx_codec_jpx_unittest.cpp

[npm, 2016-12-01 18:21:54]

The CQ bit was checked by npm@chromium.org

[commit-bot: I haz the power, 2016-12-01 18:21:58]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-12-01 18:36:45]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1480616514699200, "parent_rev":
"02759102cf998c9e937b3b65b64ed6b4c3b104bc", "commit_rev":
"9be9c3486688b84c723f41c85327abec238f15f9"}

[commit-bot: I haz the power, 2016-12-01 18:36:48]

Description was changed from

==========
Improve early return in CGifLZWDecoder::Decode

|code_size_cur| could be larger than |code_size|, so |code| could be
larger than |code_end|. If this happens, early return, since the Decode
has failed.

BUG=659417
==========

to

==========
Improve early return in CGifLZWDecoder::Decode

|code_size_cur| could be larger than |code_size|, so |code| could be
larger than |code_end|. If this happens, early return, since the Decode
has failed.

BUG=659417

Committed:
https://pdfium.googlesource.com/pdfium/+/9be9c3486688b84c723f41c85327abec238f...
==========

[commit-bot: I haz the power, 2016-12-01 18:36:49]

Committed patchset #1 (id:1) as
https://pdfium.googlesource.com/pdfium/+/9be9c3486688b84c723f41c85327abec238f...