Revert of Remove blink::WebLayerClient and WebGraphicsLayerDebugInfo.

Revert of Remove blink::WebLayerClient and WebGraphicsLayerDebugInfo. (patchset #10 id:200001 of https://codereview.chromium.org/1419913002/ )

Reason for revert:
Looks to be causing bot failures for ContextLost.WebGLContextLostInHiddenTab

Original issue's description:
> Remove blink::WebLayerClient and WebGraphicsLayerDebugInfo.
>
> It is now legal for Blink to provide an implementation of cc::LayerClient.
>
> CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel
>
> Committed: https://crrev.com/69698f992d3c6b2badd01f718c71df7a52b099fb
> Cr-Commit-Position: refs/heads/master@{#360855}

TBR=chrishtr@chromium.org,danakj@chromium.org,enne@chromium.org,esprehn@chromium.org,pdr@chromium.org,jbroman@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Committed: https://crrev.com/d32d4303200f2d9d016f8428546f3b30978726f3
Cr-Commit-Position: refs/heads/master@{#360892}

[David Yen, 2015-11-20 19:51:59]

Created Revert of Remove blink::WebLayerClient and WebGraphicsLayerDebugInfo.

[commit-bot: I haz the power, 2015-11-20 19:53:05]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1461423002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1461423002/1

[commit-bot: I haz the power, 2015-11-20 19:55:18]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-11-20 19:56:22]

Patchset 1 (id:??) landed as
https://crrev.com/d32d4303200f2d9d016f8428546f3b30978726f3
Cr-Commit-Position: refs/heads/master@{#360892}