Revert "Perfetto: Move in-process mode behind a feature flag while investigating crash"

This reverts commit 719b61dac0ba0059445013aea1a3d07e30248aa1.

Reason for revert: Causing failures of 	StartupTracingInProcessTest.TestFilledStartupBuffer on many builders

Original change's description:
> Perfetto: Move in-process mode behind a feature flag while investigating crash
> 
> R=​ssid@chromium.org
> BUG=961609
> 
> Change-Id: Ic25d4eb36f90506c8d21abf3df35fb3f11474746
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1616447
> Commit-Queue: oysteine <oysteine@chromium.org>
> Reviewed-by: ssid <ssid@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#660715}

TBR=oysteine@chromium.org,ssid@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 961609
Change-Id: I6f19fc5f738d9a1b05cb9c76438bed20e5ee45b0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1619585
Reviewed-by: Fergus Dall <sidereal@google.com>
Commit-Queue: Fergus Dall <sidereal@google.com>
Cr-Commit-Position: refs/heads/master@{#661284}
3 files changed