Enable CorbAllowlistAlsoAppliesToOorCors by default.

PSA where we announced that we are enabling this feature in M83 Canary
and Dev releases:
https://groups.google.com/a/chromium.org/forum/#!topic/chromium-extensions/aCd_OgX_aSw/discussion

Design doc:
https://docs.google.com/document/d/15QPPRwnWl5YboQ6foTM65IfFW0KHRPqHHk-IoGN04-Y

Bug: 920638, 1055980
Change-Id: I237e65a24decd204c5f26a5654f229e6a85bfcf2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2102641
Commit-Queue: Łukasz Anforowicz <lukasza@chromium.org>
Reviewed-by: Yutaka Hirano <yhirano@chromium.org>
Reviewed-by: Charlie Reis <creis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#750731}

services/network/public/cpp/features.cc

@@ -187,7 +187,7 @@ const base::FeatureParam<std::string> kEmergencyLegacyCookieAccessParam{
 // [1]
 // https://www.chromium.org/Home/chromium-security/extension-content-script-fetches
 const base::Feature kCorbAllowlistAlsoAppliesToOorCors = {
-    "CorbAllowlistAlsoAppliesToOorCors", base::FEATURE_DISABLED_BY_DEFAULT};
+    "CorbAllowlistAlsoAppliesToOorCors", base::FEATURE_ENABLED_BY_DEFAULT};
 const char kCorbAllowlistAlsoAppliesToOorCorsParamName[] =
     "AllowlistForCorbAndCors";