Revert of [WebView] Add unique visual state request ids.

Revert of [WebView] Add unique visual state request ids. (patchset #4 id:60001 of https://codereview.chromium.org/900303002/)

Reason for revert:
This is breaking some bots, see for example:
https://chromegw.corp.google.com/i/chromium.linux/builders/Android%20Arm64%20Builder%20(dbg)/builds/8923

https://chromegw.corp.google.com/i/chromium.linux/builders/Android%20Builder%20(dbg)/builds/73663

The reason is:
M D ST: Write to static field org.chromium.android_webview.AwContents.sNextVisualStateRequestId from instance method org.chromium.android_webview.AwContents.flushVisualState(AwContents$VisualStateFlushCallback)  At AwContents.java

Original issue's description:
> [WebView] Add unique visual state request ids.
>
> Each flushVisualState request returns a unique id
> that allows callers to match requests with callbacks.
> The reasoning behind is to potentially allow clients
> to reuse VisualStateFlushCallback objects to avoid
> additional java allocations.
>
> BUG=455651
>
> Committed: https://crrev.com/d011b93e7c8f966ba068b0c77c8a1400bdedee88
> Cr-Commit-Position: refs/heads/master@{#315304}

TBR=boliu@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=455651
Committed: https://crrev.com/709e3c43d4287c5ae632b6614a1d3747fe21b47b
Cr-Commit-Position: refs/heads/master@{#315321}

[Ignacio Solla, 2015-02-09 16:25:57]

Created Revert of [WebView] Add unique visual state request ids.

[commit-bot: I haz the power, 2015-02-09 16:27:21]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/907723004/1

[commit-bot: I haz the power, 2015-02-09 16:28:21]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-02-09 16:28:51]

Patchset 1 (id:??) landed as
https://crrev.com/709e3c43d4287c5ae632b6614a1d3747fe21b47b
Cr-Commit-Position: refs/heads/master@{#315321}