Don't return uninitialized memory from PDFiumEngine::Form_Response().

Don't return uninitialized memory from PDFiumEngine::Form_Response().

If the response is too long to return in the caller-supplied buffer,
truncate it to fit per the description of the app_response method in
third_party/pdfium/fpdfsdk/include/fpdfformfill.h

BUG=397834
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=286323

[Tom Sepez, 2014-07-28 19:38:38]

Lei, please review.

[Lei Zhang, 2014-07-28 20:04:50]

In third_party/pdfium/fpdfsdk/include/fpdfformfill.h, the "Method: app_response"
description says:

Return Value: Number of bytes the user input text consumes, not including
trailing zeros. If the text exceed 2048 bytes, the exceeded part will be
ignored.

So maybe we do want to truncate?

[Tom Sepez, 2014-07-28 20:29:11]

> So maybe we do want to truncate?
Yes. Serves me right for not looking deeper.

[Tom Sepez, 2014-07-28 20:39:51]

Lei, lets try again.  Thanks

[Lei Zhang, 2014-07-28 22:21:36]

lgtm

[Tom Sepez, 2014-07-29 16:02:31]

The CQ bit was checked by tsepez@chromium.org

[commit-bot: I haz the power, 2014-07-29 16:06:33]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/tsepez@chromium.org/424883002/20001

[Tom Sepez, 2014-07-29 19:15:01]

The CQ bit was unchecked by tsepez@chromium.org

[Tom Sepez, 2014-07-29 19:42:29]

Lei, per discussion with Jun, patch set #3 is actually the behaviour the API
requires.  I have a CL on the other side to clean up the comments to describe
this behviour in progress.

[Tom Sepez, 2014-07-29 19:43:25]

The CQ bit was checked by tsepez@chromium.org

[commit-bot: I haz the power, 2014-07-29 19:45:03]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/tsepez@chromium.org/424883002/40001

[Lei Zhang, 2014-07-29 19:46:08]

Ok, LGTM++

[commit-bot: I haz the power, 2014-07-29 22:48:22]

Change committed as 286323