Revert of Evict Service Worker when reading it from disk cache fails.

Revert of Evict Service Worker when reading it from disk cache fails. (patchset #2 id:20001 of https://codereview.chromium.org/1098083003/)

Reason for revert:
Broke Win 8 Aura content_browsertests

[ RUN      ] ServiceWorkerVersionBrowserTest.ReadResourceFailure
...
[2420:2792:0426/232049:1965296:FATAL:service_worker_registration.cc(44)] Check failed: ::content::BrowserThread::CurrentlyOn(BrowserThread::IO). Must be called on Chrome_IOThread; actually called on Unknown Thread.
Backtrace:
	base::debug::StackTrace::StackTrace [0x07FB1081+33]
	logging::LogMessage::~LogMessage [0x07FFD9FF+63]
	content::ServiceWorkerRegistration::~ServiceWorkerRegistration [0x045639F5+293]
	content::ServiceWorkerRegistration::`scalar deleting destructor' [0x006A087A+26]
	base::RefCounted\u003Ccontent::ServiceWorkerRegistration>::Release [0x0372C3D2+114]
	scoped_refptr\u003Ccontent::ServiceWorkerRegistration>::Release [0x03D8F94E+14]

http://build.chromium.org/p/chromium.win/builders/Win8%20Aura/builds/29227/steps/content_browsertests/logs/ServiceWorkerVersionBrowserTest.ReadResourceFailure

Original issue's description:
> Evict Service Worker when reading it from disk cache fails.
>
> If reading the SW resources from the disk cache fails, we should evict
> the worker or else we will keep getting the same failure.
>
> This patch unsets the worker from the live registration, and then
> deletes the registration if the SW was the stored version.
>
> BUG=448003
>
> Committed: https://crrev.com/64e3ffb1c6b85c7d21e63afcbffe85c5a1112eb7
> Cr-Commit-Position: refs/heads/master@{#327000}

TBR=nhiroki@chromium.org,kinuko@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=448003
Committed: https://crrev.com/d2a667eb203985ef680957fce85e1b8454e4ef26
Cr-Commit-Position: refs/heads/master@{#327012}

[falken, 2015-04-27 08:01:00]

Created Revert of Evict Service Worker when reading it from disk cache fails.

[commit-bot: I haz the power, 2015-04-27 08:01:31]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1056913010/1

[commit-bot: I haz the power, 2015-04-27 08:02:12]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-27 08:03:05]

Patchset 1 (id:??) landed as
https://crrev.com/d2a667eb203985ef680957fce85e1b8454e4ef26
Cr-Commit-Position: refs/heads/master@{#327012}