Make fake file audio input device not crash when it fails to read.

Make fake file audio input device not crash when it fails to read.

The fake device used to just CHECK when it failed to read the file,
but I noticed those checks don't make it into the logs for official
builds. This makes the --use-file-for-fake-audio-capture flag a bit
user-hostile, which has also shown up in Chrome crash reports. This
way there will be an entry in the log and the device will be silent
instead of crashing.

BUG=466408
Committed: https://crrev.com/132678eedf4fb5965f004620923569a5bad5cf31
Cr-Commit-Position: refs/heads/master@{#321365}

[phoglund_chromium, 2015-03-19 12:06:26]

phoglund@chromium.org changed reviewers:
+ henrika@chromium.org

[henrika (OOO until Aug 14), 2015-03-19 12:23:29]

LGTM

[phoglund_chromium, 2015-03-19 15:01:20]

The CQ bit was checked by phoglund@chromium.org

[commit-bot: I haz the power, 2015-03-19 15:01:30]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1018293002/1

[commit-bot: I haz the power, 2015-03-19 16:09:25]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-19 16:09:52]

Patchset 1 (id:??) landed as
https://crrev.com/132678eedf4fb5965f004620923569a5bad5cf31
Cr-Commit-Position: refs/heads/master@{#321365}