Revert of [KeyEvent Mac] Move WebInputEventFactory into chromium.

Revert of [KeyEvent Mac] Move WebInputEventFactory into chromium. (patchset #9 id:160001 of https://codereview.chromium.org/1331013004/ )

Reason for revert:
http://build.chromium.org/p/chromium.webkit/builders/WebKit%20Mac10.9%20%28retina%29/builds/6032
../../content/browser/renderer_host/input/web_input_event_builders_mac.mm:889:10: error: use of undeclared identifier 'NSEventTypeSmartMagnify'; did you mean 'NSEventTypeMagnify'?
    case NSEventTypeSmartMagnify:
         ^~~~~~~~~~~~~~~~~~~~~~~
         NSEventTypeMagnify

Original issue's description:
> [KeyEvent Mac] Move WebInputEventFactory into chromium.
>
> There was an inconsistency on the Mac platform that the WebInputEventFactory
> (old WebKit code) was being used. Other platforms have migrated to using
> builders and it was weird for the Mac code path to have some code on one
> side of the blink divide that others didn't. This change brings the Mac
> platform inline with the others by moving the input event
> factory from blink into chromium.
>
> blink change: https://codereview.chromium.org/1335673002/
>
> BUG=493833, 237267
>
> Committed: https://crrev.com/8db5ca887d4560ed15bf5e6e2dce69dc85868f25
> Cr-Commit-Position: refs/heads/master@{#348989}
>
> Committed: https://crrev.com/5405b8306550f01b86204d45fad3360593b39001
> Cr-Commit-Position: refs/heads/master@{#349157}

TBR=wez@chromium.org,sadrul@chromium.org,asvitkine@chromium.org,mnaganov@chromium.org,piman@chromium.org,thakis@chromium.org,dtapuska@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=493833, 237267
Committed: https://crrev.com/a61cdca682f430b3115d9fda3dcab3dc0352cae7
Cr-Commit-Position: refs/heads/master@{#349172}

[skobes, 2015-09-16 18:41:17]

Created Revert of [KeyEvent Mac] Move WebInputEventFactory into chromium.

[commit-bot: I haz the power, 2015-09-16 18:41:58]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1348843002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1348843002/1

[commit-bot: I haz the power, 2015-09-16 18:43:27]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-09-16 18:44:27]

Patchset 1 (id:??) landed as
https://crrev.com/a61cdca682f430b3115d9fda3dcab3dc0352cae7
Cr-Commit-Position: refs/heads/master@{#349172}

[commit-bot: I haz the power, 2015-09-23 12:58:33]

Patchset 1 (id:??) landed as
https://crrev.com/a61cdca682f430b3115d9fda3dcab3dc0352cae7
Cr-Commit-Position: refs/heads/master@{#349172}