Revert of Reset RendererAccessibility state when enabling tree only accessibility mode. (patchset #1 id:1 of https://codereview.chromium.org/1215063002/)
Revert of Reset RendererAccessibility state when enabling tree only accessibility mode. (patchset #1 id:1 of https://codereview.chromium.org/1215063002/)

Reason for revert:
Suspect this CL is the cause of test failures (OutputE2ETest.Checkbox and OutputE2ETest.ListBox) on the Linux ChromiumOS Ozone Tests bot. See http://build.chromium.org/p/chromium.chromiumos/builders/Linux%20ChromiumOS%20Ozone%20Tests%20%281%29/builds/17425

Original issue's description:
> Reset RendererAccessibility state when enabling tree only accessibility mode.
>
> When a caller of the automation extension API requests a tree (desktop or tabs) for a previously requested tree, a load complete  does not fire as a result of the request. This is problematic when the caller was not the one to make any of the previous requests.
>
> To reproduce:
> - turn on ChromeVox in OOBE
> - notice all elements are read
> - toggle ChromeVox
> - notice some elements are no longer read.
>
> This is because ChromeVox attempts to call EnableFrame() on a subtree of the desktop tree. The request on the browser side attempts to enable tree only accessibility on a rfh that already has tree only accessibility enabled. The call returns early as a result. Events fired on this subtree never get handled inside of the extension because the tree data never got sent.
>
> BUG=488693
>
> Committed: https://crrev.com/85fd9dbc7ae755de2bff42b302db1ab5f5b0f125
> Cr-Commit-Position: refs/heads/master@{#339051}

TBR=aboxhall@chromium.org,dmazzoni@chromium.org,jam@chromium.org,dtseng@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=488693

Review URL: https://codereview.chromium.org/1226123013

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#339074}

Just-D/chromium-1,Pluto-tv/chromium-crosswalk,Chilledheart/chromium,Pluto-tv/chromium-crosswalk,Pluto-tv/chromium-crosswalk,Chilledheart/chromium,Just-D/chromium-1,axinging/chromium-crosswalk,Just-D/chromium-1,Just-D/chromium-1,axinging/chromium-crosswalk,axinging/chromium-crosswalk,Just-D/chromium-1,axinging/chromium-crosswalk,Pluto-tv/chromium-crosswalk,Pluto-tv/chromium-crosswalk,Just-D/chromium-1,Chilledheart/chromium,Chilledheart/chromium,axinging/chromium-crosswalk,Pluto-tv/chromium-crosswalk,axinging/chromium-crosswalk,Pluto-tv/chromium-crosswalk,axinging/chromium-crosswalk,Pluto-tv/chromium-crosswalk,Chilledheart/chromium,axinging/chromium-crosswalk,Chilledheart/chromium,Pluto-tv/chromium-crosswalk,Chilledheart/chromium,Just-D/chromium-1,axinging/chromium-crosswalk,axinging/chromium-crosswalk,Just-D/chromium-1,axinging/chromium-crosswalk,Chilledheart/chromium,Just-D/chromium-1,Chilledheart/chromium