Revert of [DevTools] Filter any messages from previous sessions in DevToolsAgentHostImpl

Revert of [DevTools] Filter any messages from previous sessions in DevToolsAgentHostImpl (patchset #6 id:120001 of https://codereview.chromium.org/1408363004/ )

Reason for revert:
Rolling this out for breaking Inspect Element.

Original issue's description:
> [DevTools] Filter any messages from previous sessions in DevToolsAgentHostImpl
>
> Frontend can receive response for protocol message that was sent by previous session. E.g. frontend send protocol message and then reattach then get response.
> session id for procol message is added in this CL. DevToolsAgentHostImpl store current session_id, RenderFrameDevToolsAgentHost and WorkerDevToolsAgentHost add to each protocol message session id and SendResponseMessageToClient method check it after processing.
>
> BUG=503875, 503824
> TEST=run blink/tools/run_layout_tests.py inspector/sources/debugger-breakpoints/set-conditional-breakpoint.html --repeat-each 2
> R=pfeldman@chromium.org, dgozman@chromium.org, tsepez@chromium.org
> TBR=jam@chromium.org

TBR=dgozman@chromium.org,tsepez@chromium.org,kozyatinskiy@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=503875, 503824
Committed: https://crrev.com/6274dfa569f4a0c738d8a4cf9015cae27edeb249
Cr-Commit-Position: refs/heads/master@{#359257}

[pfeldman, 2015-11-12 04:21:44]

Created Revert of [DevTools] Filter any messages from previous sessions in
DevToolsAgentHostImpl

[commit-bot: I haz the power, 2015-11-12 04:22:40]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1437993003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1437993003/1

[commit-bot: I haz the power, 2015-11-12 04:24:24]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-11-12 20:04:49]

Patchset 1 (id:??) landed as
https://crrev.com/6274dfa569f4a0c738d8a4cf9015cae27edeb249
Cr-Commit-Position: refs/heads/master@{#359257}