Revert of Re-enable the activation behavior of media elements (click to play/pause)

Revert of Re-enable the activation behavior of media elements (click to play/pause) (patchset #3 id:40001 of https://codereview.chromium.org/830183005/)

Reason for revert:
breaks androidwebview_instrumentation_tests on Android Tests (dbg) on chromium.webkit starting with http://build.chromium.org/p/chromium.webkit/builders/Android%20Tests%20%28dbg%29/builds/23717

Original issue's description:
> Re-enable the activation behavior of media elements (click to play/pause)
> 
> This revives most of the code and tests from an earlier revert:
> https://codereview.chromium.org/249483002
> 
> The "Don't fire events when interacting with <video controls>" bug has
> been fixed, so the native controls and scripted controls will no
> longer compete for control:
> https://codereview.chromium.org/406213002
> 
> The definition of "restrained media controller" has been simplified in
> spec and implementation since the last time:
> https://codereview.chromium.org/262463003
> 
> BUG=354746
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=188141

TBR=fs@opera.com,aberent@chromium.org,philipj@opera.com
NOTREECHECKS=true
NOTRY=true
BUG=354746
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=188160

[jbudorick, 2015-01-09 17:57:51]

Created Revert of Re-enable the activation behavior of media elements (click to
play/pause)

[commit-bot: I haz the power, 2015-01-09 17:58:01]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/839293002/1

[commit-bot: I haz the power, 2015-01-09 17:59:01]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=188160