Revert of Add Autofill to the <webview> chrome://chrome-signin page

Revert of Add Autofill to the <webview> chrome://chrome-signin page (patchset #12 id:340001 of https://codereview.chromium.org/866523002/)

Reason for revert:
Introduced crashes in ManagePasswordsUIController::OnPasswordSubmitted:(

https://crash.corp.google.com/browse?q=product.name%3D%27Chrome%27%20AND%20product.version%3D%2742.0.2309.0%27%20AND%20custom_data.ChromeCrashProto.channel%3D%27canary%27%20AND%20custom_data.ChromeCrashProto.ptype%3D%27browser%27%20AND%20custom_data.ChromeCrashProto.magic_signature_1.name%3D%27ManagePasswordsUIController%3A%3AOnPasswordSubmitted%27

Original issue's description:
> Add Autofill to the <webview> chrome://chrome-signin page
>
> The change in the chrome_autofill_client.cc is needed to enable the autofill popup on
> Mac.
>
> BUG=447938
> TEST=Start Chrome. Navigate to chrome://chrome-signin. Enter a correct username
> with an incorrect password. After the password error appears, you should be able
> to autofill that username.
>
> Committed: https://crrev.com/4a1e13b16b5ef2cb6f7c800ad3c08f1f44bef285
> Cr-Commit-Position: refs/heads/master@{#314889}
>
> Committed: https://crrev.com/e6d3ca36ec225b0e13e385318c6c4f35fad4ca47
> Cr-Commit-Position: refs/heads/master@{#316899}

TBR=estade@chromium.org,fsamuel@chromium.org,lazyboy@chromium.org,vabr@chromium.org,engedy@chromium.org,jww@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=447938
Committed: https://crrev.com/9139a6a15340268d12a95abc8f572887454e1ee9
Cr-Commit-Position: refs/heads/master@{#317105}

[noms (inactive), 2015-02-19 19:39:00]

Created Revert of Add Autofill to the <webview> chrome://chrome-signin page

[commit-bot: I haz the power, 2015-02-19 19:41:25]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/944513002/1

[commit-bot: I haz the power, 2015-02-19 19:42:38]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-02-19 19:43:21]

Patchset 1 (id:??) landed as
https://crrev.com/9139a6a15340268d12a95abc8f572887454e1ee9
Cr-Commit-Position: refs/heads/master@{#317105}