Log serial read and write errors on Windows.

Log serial read and write errors on Windows.

Log platform errors so that it is possible to determine from logs what
caused the chrome.serial API to return the generic "system_error"
message.

Committed: https://crrev.com/114441175e97285f358623c493a39710b9613ff2
Cr-Commit-Position: refs/heads/master@{#330870}

[Reilly Grant (use Gerrit), 2015-05-21 00:26:01]

reillyg@chromium.org changed reviewers:
+ rockot@chromium.org

[Reilly Grant (use Gerrit), 2015-05-21 00:29:20]

Ken, please take a look.

[Ken Rockot(use gerrit already), 2015-05-21 00:30:35]

lgtm

[Reilly Grant (use Gerrit), 2015-05-21 01:15:09]

The CQ bit was checked by reillyg@chromium.org

[commit-bot: I haz the power, 2015-05-21 01:16:27]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1147223002/1

[commit-bot: I haz the power, 2015-05-21 01:38:54]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-05-21 01:39:46]

Patchset 1 (id:??) landed as
https://crrev.com/114441175e97285f358623c493a39710b9613ff2
Cr-Commit-Position: refs/heads/master@{#330870}