Remove support for custom NSURLProtocol.

Remove support for custom NSURLProtocol.

WKWebView does not support custom NSURLProtocol (see discussion
in https://bugs.webkit.org/show_bug.cgi?id=138169). Remove the
interception code as it is never called.

BUG=665036, 585700

[sdefresne, 2017-01-12 17:17:54]

The CQ bit was checked by sdefresne@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2017-01-12 17:18:21]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[sdefresne, 2017-01-12 17:19:11]

sdefresne@chromium.org changed reviewers:
+ eugenebut@chromium.org

[sdefresne, 2017-01-12 17:19:11]

I chose not to remove the class implementing the functionality in order to
reduce the size of the CL. Please take a look. AFAICT, this NSURLProtocol
handler is never invoked with WKWebView.

[Eugene But (OOO till 7-30), 2017-01-12 17:24:08]

eugenebut@chromium.org changed reviewers:
+ bzanotti@chromium.org

[Eugene But (OOO till 7-30), 2017-01-12 17:24:09]

This is still used by UIWebView and Chrome may still be using UIWebView for
SignIn. Benoit, do you think this change is harmless to SignIn?

[sdefresne, 2017-01-12 17:31:41]

On 2017/01/12 17:24:09, Eugene But wrote:
> This is still used by UIWebView and Chrome may still be using UIWebView for
> SignIn. Benoit, do you think this change is harmless to SignIn?

AFAIK, SignIn now uses SFSafariViewController and no longer UIWebView.

I've tested and I'm able to sign-in in Chrome with this CL applied and I've
confirmed that I'm logged in the content area. Is there anything else that could
be broken?

[Eugene But (OOO till 7-30), 2017-01-12 17:40:23]

Thanks for checking. lgtm, but could you please wait for Benoit's response.

[bzanotti, 2017-01-12 17:56:40]

On 2017/01/12 17:31:41, sdefresne wrote:
> On 2017/01/12 17:24:09, Eugene But wrote:
> > This is still used by UIWebView and Chrome may still be using UIWebView for
> > SignIn. Benoit, do you think this change is harmless to SignIn?
> 
> AFAIK, SignIn now uses SFSafariViewController and no longer UIWebView.
> 
> I've tested and I'm able to sign-in in Chrome with this CL applied and I've
> confirmed that I'm logged in the content area. Is there anything else that
could
> be broken?

Not LGTM.

SignIn is still using UIWebView (on a basic Chromium build, you need to tap the
experimental setting "Disable SafariVCSignIn"). We still need custom support of
NSURLProtocol for this.