Add code for formatting the X-Client-Data header in devtools

This is essentially pulling
https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/2351775
into the Chromium repo, so that it can be maintained alongside the proto
definition that it is parsing and formatting.

R=mathias

Bug: 1103854
Change-Id: I25707cf94678682d856f085b3aa259b02361dfa0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2360517
Reviewed-by: Mathias Bynens <[email protected]>
Reviewed-by: Dirk Pranke <[email protected]>
Commit-Queue: Ilya Sherman <[email protected]>
Cr-Commit-Position: refs/heads/master@{#799228}
diff --git a/PRESUBMIT.py b/PRESUBMIT.py
index ef45d81f..023d07c 100644
--- a/PRESUBMIT.py
+++ b/PRESUBMIT.py
@@ -12,7 +12,7 @@
 _EXCLUDED_PATHS = (
     # Generated file.
     (r"^components[\\/]variations[\\/]proto[\\/]devtools[\\/]"
-     r"client_variations_parser.js"),
+     r"client_variations.js"),
     r"^native_client_sdk[\\/]src[\\/]build_tools[\\/]make_rules.py",
     r"^native_client_sdk[\\/]src[\\/]build_tools[\\/]make_simple.py",
     r"^native_client_sdk[\\/]src[\\/]tools[\\/].*.mk",