Revert of Revert of [DevTools] Check request_id in DevToolsUIBindings::IndexPath

Revert of Revert of [DevTools] Check request_id in DevToolsUIBindings::IndexPath (patchset #2 id:40001 of https://codereview.chromium.org/956873002/)

Reason for revert:
Turns out the revert was incorrect (the error even started happening a couple builds before this patch).

Original issue's description:
> Revert of [DevTools] Check request_id in DevToolsUIBindings::IndexPath (patchset #1 id:1 of https://codereview.chromium.org/951953002/)
>
> Reason for revert:
> Speculative revert: http://build.chromium.org/p/chromium.mac/builders/Mac10.6%20Tests/builds/4683/steps/browser_tests%20on%20Mac-10.6/logs/DevToolsSanityTest.TestReattachAfterCrash became very flaky on Mac OS X 10.6 about when this patch was introduced. This is the only devtools change near to the start of the flakiness.
>
> The errors are:
> DevToolsSanityTest.TestReattachAfterCrash (run #1):
> [ RUN      ] DevToolsSanityTest.TestReattachAfterCrash
> [32422:28675:0224/105826:WARNING:data_reduction_proxy_config.cc(211)] SPDY proxy OFF at startup
> HTTP server started on http://127.0.0.1:64960...
> sending server_data: {"host": "127.0.0.1", "port": 64960} (36 bytes)
> [32427:9479:0224/105828:WARNING:channel.cc(547)] Failed to send message to ack remove remote endpoint (local ID 1, remote ID 1)
> [32427:9479:0224/105828:WARNING:channel.cc(547)] Failed to send message to ack remove remote endpoint (local ID 2147483648, remote ID 2
>
> Original issue's description:
> > [DevTools] Check request_id in DevToolsUIBindings::IndexPath
> >
> > If request_id is reused before the previous job with the same id is finished the old job won't be stopped in ~DevToolsUIBindings.
> >
> > BUG=
> >
> > Committed: https://crrev.com/88ac3ce8fa6463e5f04d4b3e7e2327e2ec1b3a19
> > Cr-Commit-Position: refs/heads/master@{#317799}
>
> TBR=dgozman@chromium.org,vkuzkokov@chromium.org
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=
>
> Committed: https://crrev.com/012bebf20cabd5a81179a185b87bd75f632edb66
> Cr-Commit-Position: refs/heads/master@{#318019}

TBR=dgozman@chromium.org,vkuzkokov@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=

Committed: https://crrev.com/c9f3e567970c153dd3526daf601da24520a6aff5
Cr-Commit-Position: refs/heads/master@{#318024}

[phoglund_chromium, 2015-02-25 11:09:55]

Created Revert of Revert of [DevTools] Check request_id in
DevToolsUIBindings::IndexPath

[commit-bot: I haz the power, 2015-02-25 11:10:35]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/957623003/1

[commit-bot: I haz the power, 2015-02-25 11:11:07]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-02-25 11:11:53]

Patchset 1 (id:??) landed as
https://crrev.com/c9f3e567970c153dd3526daf601da24520a6aff5
Cr-Commit-Position: refs/heads/master@{#318024}