Add more instrumentation to diagnose an Android renderer crash.
Add more instrumentation to diagnose an Android renderer crash.

We want to know the content of --force-fieldtrials= flag at
the time the CHECK is hit - particularly whether the trial
being set is there or not. In a previous CL, I added the logging
of this string, but turns it the CHECK message gets truncated.
This CL adds extra logic to take the substring of the switch
starting at the trial name, if it exists.

BUG=359406

Review URL: https://codereview.chromium.org/1592433002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#369552}

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