Add context to file load failures in pdfium_test.

Add context to file load failures in pdfium_test.

Currently if pdfium_test fails to load the document it just says it failed. This
CL adds some extra context by looking at the error set by the load and reporting
it to the user.

R=tsepez@chromium.org

Committed: https://pdfium.googlesource.com/pdfium/+/e6eae266a48cdcfd464f52df68c97183a4f7987a

[dsinclair, 2015-10-27 14:19:19]

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

[dsinclair, 2015-10-27 14:19:20]

PTAL.

[Tom Sepez, 2015-10-27 16:25:36]

LGTM after fixing nit.

https://codereview.chromium.org/1413923006/diff/1/samples/pdfium_test.cc
File samples/pdfium_test.cc (right):

https://codereview.chromium.org/1413923006/diff/1/samples/pdfium_test.cc#newc...
samples/pdfium_test.cc:418: fprintf(stderr, "Unknown error %ld\n", err);
nit: \n not needed here.

[dsinclair, 2015-10-27 17:02:33]

https://codereview.chromium.org/1413923006/diff/1/samples/pdfium_test.cc
File samples/pdfium_test.cc (right):

https://codereview.chromium.org/1413923006/diff/1/samples/pdfium_test.cc#newc...
samples/pdfium_test.cc:418: fprintf(stderr, "Unknown error %ld\n", err);
On 2015/10/27 16:25:36, Tom Sepez wrote:
> nit: \n not needed here.

Done.

[dsinclair, 2015-10-27 17:03:03]

Committed patchset #2 (id:20001) manually as
e6eae266a48cdcfd464f52df68c97183a4f7987a (presubmit successful).