Revert of Add EnabledStateObserver to BackgroundTracingManager

Revert of Add EnabledStateObserver to BackgroundTracingManager (patchset #3 id:130001 of https://codereview.chromium.org/2769963005/ )

Reason for revert:
This CL causes tests failures (browser_side_navigation_content_browsertests, content_browsertests, site_per_process_content_browsertests). 

https://findit-for-me.appspot.com/waterfall/build-failure?url=https://build.chromium.org/p/chromium.chromiumos/builders/Linux%20ChromiumOS%20Tests%20%28dbg%29%281%29/builds/24171

Original issue's description:
> Add EnabledStateObserver to BackgroundTracingManager
> 
> This CL removes the memory-infra related code into memory-tracing
> observer. Also the tests implement the observer instead of setting
> callbacks.
> 
> BUG=700245
> 
> Review-Url: https://codereview.chromium.org/2769963005
> Cr-Commit-Position: refs/heads/master@{#460293}
> Committed: https://chromium.googlesource.com/chromium/src/+/f64ac5cb273e3abab3564f1a5997b3da164ab9ff

TBR=oysteine@chromium.org,alexmos@chromium.org,ssid@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=700245
Review-Url: https://codereview.chromium.org/2785663002
Cr-Commit-Position: refs/heads/master@{#460343}
Committed: https://chromium.googlesource.com/chromium/src/+/88d07c763d35621da2c62b9f18822109bbd7a261

[kolos1, 2017-03-29 10:43:25]

The CQ bit was checked by kolos@chromium.org

[kolos1, 2017-03-29 10:43:25]

Created Revert of Add EnabledStateObserver to BackgroundTracingManager

[commit-bot: I haz the power, 2017-03-29 10:43:47]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-03-29 10:44:39]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1490784205595340, "parent_rev":
"1690551c93020ef0ebee1e0a1a523c089ce3d62f", "commit_rev":
"88d07c763d35621da2c62b9f18822109bbd7a261"}

[commit-bot: I haz the power, 2017-03-29 10:45:26]

Description was changed from

==========
Revert of Add EnabledStateObserver to BackgroundTracingManager (patchset #3
id:130001 of https://codereview.chromium.org/2769963005/ )

Reason for revert:
This CL causes tests failures (browser_side_navigation_content_browsertests,
content_browsertests, site_per_process_content_browsertests). 

https://findit-for-me.appspot.com/waterfall/build-failure?url=https://build.c...

Original issue's description:
> Add EnabledStateObserver to BackgroundTracingManager
> 
> This CL removes the memory-infra related code into memory-tracing
> observer. Also the tests implement the observer instead of setting
> callbacks.
> 
> BUG=700245
> 
> Review-Url: https://codereview.chromium.org/2769963005
> Cr-Commit-Position: refs/heads/master@{#460293}
> Committed:
https://chromium.googlesource.com/chromium/src/+/f64ac5cb273e3abab3564f1a5997...

TBR=oysteine@chromium.org,alexmos@chromium.org,ssid@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=700245
==========

to

==========
Revert of Add EnabledStateObserver to BackgroundTracingManager (patchset #3
id:130001 of https://codereview.chromium.org/2769963005/ )

Reason for revert:
This CL causes tests failures (browser_side_navigation_content_browsertests,
content_browsertests, site_per_process_content_browsertests). 

https://findit-for-me.appspot.com/waterfall/build-failure?url=https://build.c...

Original issue's description:
> Add EnabledStateObserver to BackgroundTracingManager
> 
> This CL removes the memory-infra related code into memory-tracing
> observer. Also the tests implement the observer instead of setting
> callbacks.
> 
> BUG=700245
> 
> Review-Url: https://codereview.chromium.org/2769963005
> Cr-Commit-Position: refs/heads/master@{#460293}
> Committed:
https://chromium.googlesource.com/chromium/src/+/f64ac5cb273e3abab3564f1a5997...

TBR=oysteine@chromium.org,alexmos@chromium.org,ssid@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=700245

Review-Url: https://codereview.chromium.org/2785663002
Cr-Commit-Position: refs/heads/master@{#460343}
Committed:
https://chromium.googlesource.com/chromium/src/+/88d07c763d35621da2c62b9f1882...
==========

[commit-bot: I haz the power, 2017-03-29 10:45:27]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/88d07c763d35621da2c62b9f1882...

[ssid, 2017-03-29 17:50:20]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/2782933002/ by ssid@chromium.org.

The reason for reverting is: |config_| can be null. So, do not dereference it..