Pepper: Always call status_cb in FileDownloader.

Pepper: Always call status_cb in FileDownloader.

FileDownloader assumed that implementations of blink::WebURLLoader would always
call didFail and didFinishLoading, which is not the case. In the cases where
didFinishLoading was not called, FileDownloader would never run the status
callback, preventing any error reporting from happening.

This change deletes the implementation of blink::WebURLLoader in didFail and
invokes status_cb, allowing error reporting to work properly, and for memory to
be cleaned up.

BUG=440180
Committed: https://crrev.com/d800932db8b677c81d8c5d2f0e704168dba03c75
Cr-Commit-Position: refs/heads/master@{#315649}

[teravest, 2015-02-10 20:00:08]

teravest@chromium.org changed reviewers:
+ dmichael@chromium.org

[dmichael (off chromium), 2015-02-10 21:34:21]

lgtm

[teravest, 2015-02-10 21:40:13]

The CQ bit was checked by teravest@chromium.org

[commit-bot: I haz the power, 2015-02-10 21:41:18]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/909233002/1

[commit-bot: I haz the power, 2015-02-10 21:46:03]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-02-10 21:46:52]

Patchset 1 (id:??) landed as
https://crrev.com/d800932db8b677c81d8c5d2f0e704168dba03c75
Cr-Commit-Position: refs/heads/master@{#315649}