Revert of Set RequestContextObject for PNaCl pexe fetches, to fix On-Demand update.

Revert of Set RequestContextObject for PNaCl pexe fetches, to fix On-Demand update. (patchset #5 of https://codereview.chromium.org/471233003/)

Reason for revert:
Test is failing on a Blink bot on ChromeOS

Original issue's description:
> Set RequestContextObject for PNaCl pexe fetches, to fix On-Demand update.
> 
> Add more checks to test to detect that the resource type of
> the URL request is indeed OBJECT.
> Would like to get this merged to the M38 branch.
> 
> BUG=401755
> 
> Committed: https://chromium.googlesource.com/chromium/src/+/bfc3e122d6721ccc93f0f8b19dac4a3c2a0c947d

TBR=teravest@chromium.org,ncbray@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=401755
Committed: https://crrev.com/22bb605b63b7a9fd638fad58c8bc8f985aacd9cd
Cr-Commit-Position: refs/heads/master@{#292522}

[jvoung (off chromium), 2014-08-29 00:33:11]

Created Revert of Set RequestContextObject for PNaCl pexe fetches, to fix
On-Demand update.

[commit-bot: I haz the power, 2014-08-29 00:34:12]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/jvoung@chromium.org/524483002/1

[commit-bot: I haz the power, 2014-08-29 00:35:24]

Committed patchset #1 (id:1) as 45f028b0270cc0ce0d2753c35dc3d6ed5fab06e7

[commit-bot: I haz the power, 2014-09-10 03:04:22]

Patchset 1 (id:??) landed as
https://crrev.com/22bb605b63b7a9fd638fad58c8bc8f985aacd9cd
Cr-Commit-Position: refs/heads/master@{#292522}