[Merge 103] Allow legacy JSON format for extensino schema

Allow legacy JSON format for extension schema definition which includes
C++ style comments.

(cherry picked from commit 1dac28b)

Bug: 1314077
Change-Id: I344733c47158018f89100f0aed6b667b0e101d31
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3665197
Auto-Submit: Owen Min <zmin@chromium.org>
Reviewed-by: Julian Pastarmov <pastarmovj@chromium.org>
Commit-Queue: Julian Pastarmov <pastarmovj@chromium.org>
Cr-Original-Commit-Position: refs/heads/main@{#1007314}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3673818
Commit-Queue: Owen Min <zmin@chromium.org>
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/branch-heads/5060@{#312}
Cr-Branched-From: b83393d-refs/heads/main@{#1002911}

components/policy/core/common/schema.cc

@@ -1445,7 +1445,8 @@ absl::optional<base::Value> Schema::ParseToDictAndValidate(
     std::string* error) {
   base::JSONReader::ValueWithError value_with_error =
       base::JSONReader::ReadAndReturnValueWithError(
-          schema, base::JSONParserOptions::JSON_ALLOW_TRAILING_COMMAS);
+          schema, base::JSONParserOptions::JSON_ALLOW_TRAILING_COMMAS |
+                      base::JSONParserOptions::JSON_PARSE_CHROMIUM_EXTENSIONS);
   *error = value_with_error.error_message;
 
   if (!value_with_error.value)