Revert of [Extensions Page] Send a profile changed event when developer mode changes...

Revert of [Extensions Page] Send a profile changed event when developer mode changes (patchset #2 id:20001 of https://codereview.chromium.org/1275663003/ )

Reason for revert:
Suspect it broke  Linux ChromiumOS Tests

https://build.chromium.org/p/chromium.chromiumos/builders/Linux%20ChromiumOS%20Tests%20%281%29/builds/7163

BasicExtensionSettingsWebUITest.testDeveloperModeManyExtensions (run #2):
[ RUN      ] BasicExtensionSettingsWebUITest.testDeveloperModeManyExtensions
[23730:23730:0806/145316:WARNING:chrome_browser_main_chromeos.cc(290)] Running as stub user with profile dir: test-user
[23730:23730:0806/145316:INFO:audio_manager_pulse.cc(258)] Failed to connect to the context.  Error: Connection refused
Xlib:  extension "RANDR" missing on display ":9".
[23730:23762:0806/145316:WARNING:local_extension_cache.cc(260)] Extensions will not be installed from update URLs until /var/cache/external_cache/.initialized exists.
[23730:23730:0806/145316:WARNING:child_account_service.cc(292)] User instance wasn't found while setting child account flag.
[23730:23746:0806/145316:WARNING:freezer_cgroup_process_manager.cc(58)] Cgroup freezer does not exist or is not writable. Unable to freeze renderer processes.
[23730:23730:0806/145316:ERROR:device_event_log_impl.cc(167)] [14:53:16.756] USB: usb_service_impl.cc:541 Failed to initialize libusb: Other error
[23730:23730:0806/145316:INFO:CONSOLE(5)] "line1", source: chrome-extension://pdlpifnclfacjobnmbpngemkalkjamnf/script.js (5)
[23730:23730:0806/145316:INFO:CONSOLE(6)] "line2", source: chrome-extension://pdlpifnclfacjobnmbpngemkalkjamnf/script.js (6)
[23730:23730:0806/145317:WARNING:CONSOLE(0)] "/deep/ combinator is deprecated. See https://www.chromestatus.com/features/6750456638341120 for more details.", source:  (0)
[23730:23730:0806/145317:INFO:CONSOLE(1324)] "Running TestCase BasicExtensionSettingsWebUITest.testDeveloperModeManyExtensions", source: test_api.js (1324)
[23730:23730:0806/145317:ERROR:CONSOLE(0)] "Error in response to developerPrivate.getProfileConfiguration: Error: Test Error assertTrue(this.steps.length > 0): false", source: chrome://extensions-frame/ (0)
[23730:23730:0806/145317:ERROR:CONSOLE(0)] "Error in response to developerPrivate.getProfileConfiguration: Error: Test Error assertTrue(this.steps.length > 0): false", source: chrome://extensions-frame/ (0)
[23730:23730:0806/145317:ERROR:web_ui_browser_test.cc(455)] Encountered javascript console error(s)
obj/chrome/browser_tests.gen/chrome/browser/ui/webui/extensions/extension_settings_browsertest-gen.cc:46: Failure
Value of: RunJavascriptTestF(true, "BasicExtensionSettingsWebUITest", "testDeveloperModeManyExtensions")
  Actual: false
Expected: true
[  FAILED  ] BasicExtensionSettingsWebUITest.testDeveloperModeManyExtensions, where TypeParam =  and GetParam() =  (837 ms)

Original issue's description:
> [Extensions Page] Send a profile changed event when developer mode changes
>
> Developer mode can affect the presence of certain items on the page, like the
> collect errors checkbox. Send an event notifying of the profile change when this
> happens.
>
> BUG=516583
>
> Committed: https://crrev.com/34644bb031a339d2897c210f228e633e0999a11b
> Cr-Commit-Position: refs/heads/master@{#342192}

TBR=kalman@chromium.org,rdevlin.cronin@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=516583

Review URL: https://codereview.chromium.org/1277083002

Cr-Commit-Position: refs/heads/master@{#342226}