it's used by chrome for tracing I think (?), either way, webview can certainly enable it, but should restore the original value when done

but as with all global resources that can be modified by both app and webview, this can't ever work perfectly

Yeah, I think that's correct, it's a chrome thing that WebView also takes advantage of.

I originally wanted to restore the old value, since that's probably the best fix, but Looper has no public accessor for that value. The best alternative is probably to just avoid setting things to null unless Chrome logging was previously enabled.

This is buggy in the case where an app is logging things *and* WebView is logging things, but that seems like a rare case, and I'm not sure how to solve it properly without modifying the Looper API.

I know it is super ugly, and it is sth we stay away, but it is a private field after all :)

Try to solve it without using it though.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/0c54bb9b87180c4eb1fea08afae89848111ea3ad

commit 0c54bb9b87180c4eb1fea08afae89848111ea3ad
Author: ntfschr <ntfschr@chromium.org>
Date: Fri Sep 30 02:45:40 2016

Fix Chromium tracing to not override app logging

Modify TraceEvent to only override tracing when it has been previously set by
Chromium, not for when other apps have set it.

BUG= 651215 

Review-Url: https://codereview.chromium.org/2380563003
Cr-Commit-Position: refs/heads/master@{#422016}

[modify] https://crrev.com/0c54bb9b87180c4eb1fea08afae89848111ea3ad/base/android/java/src/org/chromium/base/TraceEvent.java

Bulk edit: marking stale 'fixed' bugs as 'verified' since they don't need verification at this point.