Revert "[DevTools] Roll inspector_protocol to a6bdf8a7cc95ee954ba2f701d10f4ecf03e86539."

This reverts commit 6efe9b2a40ddd38d750e0d8ddb608608d7b2d559.

Reason for revert: Newly added test is failing on win-asan:
https://ci.chromium.org/p/chromium/builders/ci/win-asan/3917

Original change's description:
> [DevTools] Roll inspector_protocol to a6bdf8a7cc95ee954ba2f701d10f4ecf03e86539.
> 
> Also:
> (1) Make a source_set in content/browser/devtools for the encoding_test,
> and add the test to content_unittest. This will ensure that further
> changes to our test won't break after the try-bots pass a submission
> to Chromium. I've broken the tree twice with that, previously.
> (2) third_party/inspector_protocol/BUILD.gn is now a different file
> than it is upstream. But the good news is it's really really simple.
> I've updated roll.py accordingly.
> 
> Change-Id: Idbc56a183e0a1eb71ac0930c5f1f4118f6677240
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1516047
> Reviewed-by: Pavel Feldman <pfeldman@chromium.org>
> Reviewed-by: Victor Costan <pwnall@chromium.org>
> Commit-Queue: Johannes Henkel <johannes@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#640411}

TBR=caseq@chromium.org,pfeldman@chromium.org,pwnall@chromium.org,johannes@chromium.org

Change-Id: I9ed750411777ea7fe7240027c60caedb68d62ae3
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1522494
Reviewed-by: Alice Boxhall <aboxhall@chromium.org>
Commit-Queue: Alice Boxhall <aboxhall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#640615}
36 files changed