GitLab

This CL changes the tracker's trace object to a stringstream, allowing
the logging of more types of data. This CL also takes advantage of said
feature to log |begin_main_frame_data_.previous_sequence| and
|args.sequence_number| in ReportBeginMainFrame() and
ReportMainFrameCausedNoDamage().

Bug: 1017291
Change-Id: I81330b10fa2347658587ee1f9e320fb185ae35cd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1903609Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>
Commit-Queue: Mingjing Zhang <mjzhang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#713621}