Allow Tast test extension for supervised users

Tast is using a Chrome extension for testing supervised users, but
extensions are blocked by default for supervised users. This CL hard-
codes the Tast extension id and always allows it.

Bug: 1068265
Change-Id: I2ba7f66877c3113db6da5b55a47d5c007b5c95db
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2144469Reviewed-by: Aga Wronska <agawronska@chromium.org>
Commit-Queue: Toby Huang <tobyhuang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#759152}

chrome/browser/supervised_user/supervised_user_service.cc

@@ -89,6 +89,15 @@ const char kBlacklistURL[] =
 // The filename under which we'll store the blacklist (in the user data dir).
 const char kBlacklistFilename[] = "su-blacklist.bin";
 
+#if BUILDFLAG(ENABLE_EXTENSIONS)
+// These extensions are allowed for supervised users for internal development
+// purposes.
+constexpr char const* kAllowlistExtensionIds[] = {
+    "behllobkkfkfnphdnhnkndlbkcpglgmj"  // Tast extension.
+};
+
+#endif  // BUILDFLAG(ENABLE_EXTENSIONS)
+
 const char* const kCustodianInfoPrefs[] = {
     prefs::kSupervisedUserCustodianName,
     prefs::kSupervisedUserCustodianEmail,
@@ -763,6 +772,10 @@ SupervisedUserService::ExtensionState SupervisedUserService::GetExtensionState(
     return ExtensionState::ALLOWED;
   }
 
+  if (base::Contains(kAllowlistExtensionIds, extension.id())) {
+    return ExtensionState::ALLOWED;
+  }
+
   if (base::FeatureList::IsEnabled(
           supervised_users::kSupervisedUserAllowlistExtensionInstall)) {
     extensions::ExtensionManagement* management =