Revert of Update extensions::MessagingBindings to use WebScopedWindowFocusAllowedIndicator with...

Revert of Update extensions::MessagingBindings to use WebScopedWindowFocusAllowedIndicator with WebDocument. (patchset #1 id:1 of https://codereview.chromium.org/786403003/)

Reason for revert:
This CL or its dependency in blink (https://codereview.chromium.org/803253003/) is the suspected source of issue 441968 (very prominent renderer crash), among other crashes.

Original issue's description:
> Update extensions::MessagingBindings to use WebScopedWindowFocusAllowedIndicator with WebDocument.
>
> This will allow Blink to delete some deprecated code.
>
> This is part of a three-sided CL:
> Part 1: https://codereview.chromium.org/777483004/
> Part 2: <this>
> Part 3: https://codereview.chromium.org/722423004
>
> BUG=440740
>
> Committed: https://crrev.com/ebb4bf8090b06979fd44411af69304b505681f4d
> Cr-Commit-Position: refs/heads/master@{#307914}

TBR=scheib@chromium.org,mlamouri@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=440740
Committed: https://crrev.com/7e0846da8d2da2c0cda56af8c180bcdefb08c046
Cr-Commit-Position: refs/heads/master@{#308506}

[Ken Rockot(use gerrit already), 2014-12-16 02:27:17]

Created Revert of Update extensions::MessagingBindings to use
WebScopedWindowFocusAllowedIndicator with WebDocument.

[Ken Rockot(use gerrit already), 2014-12-16 02:37:28]

rockot@chromium.org changed reviewers:
+ amineer@chromium.org

[Ken Rockot(use gerrit already), 2014-12-16 02:37:28]

CL isn't being updated for some reason (think it's a rietveld bug with subject
length), but this has landed. +amineer FYI