Revert "Update IdentityManager to own ProfileOAuth2TokenService."

This reverts commit 5a8aa78d74b9f2cde6572c68603adb76ae8a40cd.

Reason for revert: Causing test failures due to cast from IdentityManagerWrapper to TestIdentityManagerWrapper. Logs:
- https://logs.chromium.org/logs/chromium/buildbucket/cr-buildbucket.appspot.com/8916648927362689184/+/steps/browser_tests/0/logs/Deterministic_failure:_GetAuthTokenFunctionTest.InteractiveApprovalSuccess__status_CRASH_/0
- https://logs.chromium.org/logs/chromium/buildbucket/cr-buildbucket.appspot.com/8916648927362689184/+/steps/browser_tests/0/logs/Deterministic_failure:_ChromePasswordProtectionServiceBrowserTest.ChromeEnterprisePasswordAlertMode__status_CRASH_/0

Original change's description:
> Update IdentityManager to own ProfileOAuth2TokenService.
> 
> With this change, ProfileOAuth2TokenService is now constructed only when
> creating an IdentityManager, eliminating the need for
> ProfileOAuth2TokenService factories.
> 
> 
> Change-Id: Ie52e179058ef87193bbf6cb0dda45208392c9572
> Bug: 939372
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1529018
> Reviewed-by: David Roger <droger@chromium.org>
> Reviewed-by: Sylvain Defresne <sdefresne@chromium.org>
> Reviewed-by: Colin Blundell <blundell@chromium.org>
> Commit-Queue: Lowell Manners <lowell@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#649073}

TBR=droger@chromium.org,blundell@chromium.org,sdefresne@chromium.org,lowell@chromium.org

Change-Id: Ie3c8a6f0188d27d2b05809f581c1e560e248df8f
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 939372
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1559389
Reviewed-by: Collin Baker <collinbaker@chromium.org>
Commit-Queue: Collin Baker <collinbaker@chromium.org>
Cr-Commit-Position: refs/heads/master@{#649137}
26 files changed