Prevent regular users from affecting supervised user UMA metrics

ChromeManagementAPIDelegate::EnableExtension() is shared by both
regular and supervised users. This function calls
SupervisedUserService::AddOrUpdateExtensionApproval() which triggers
the kSupervisedUserApprovedExtensions syncable pref and the
SupervisedUsers.Extensions UMA histogram. Place guards in
AddOrUpdateExtensionApproval() and RemoveExtensionApproval() to only
permit supervised users.

Bug: 1073722
Change-Id: I16d73056d1002ce33d68705e7ceed3f6f961c9df
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2162134Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Reviewed-by: Dan S <danan@chromium.org>
Commit-Queue: Toby Huang <tobyhuang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#762054}

chrome/browser/extensions/extension_service_sync_unittest.cc

@@ -2822,6 +2822,26 @@ TEST_F(ExtensionServiceTestSupervised, ExtensionsLiteThemesAllowed) {
   EXPECT_TRUE(registry()->enabled_extensions().Contains(id));
 }
 
+// Tests that regular users are not affecting supervised user UMA metrics.
+TEST_F(ExtensionServiceTestSupervised,
+       RegularUsersNotAffectingSupervisedUserMetrics) {
+  InitServices(/*profile_is_supervised=*/false);
+
+  base::HistogramTester histogram_tester;
+
+  base::FilePath path = data_dir().AppendASCII("good.crx");
+  const Extension* extension = InstallCRX(path, INSTALL_NEW);
+  ASSERT_TRUE(extension);
+
+  supervised_user_service()->AddOrUpdateExtensionApproval(*extension);
+
+  histogram_tester.ExpectTotalCount("SupervisedUsers.Extensions", 0);
+
+  supervised_user_service()->RemoveExtensionApproval(*extension);
+
+  histogram_tester.ExpectTotalCount("SupervisedUsers.Extensions", 0);
+}
+
 #endif  // BUILDFLAG(ENABLE_SUPERVISED_USERS)
 
 // Tests sync behavior in the case of an item that starts out as an app and gets

chrome/browser/supervised_user/supervised_user_service.cc

@@ -342,6 +342,8 @@ void SupervisedUserService::SetPrimaryPermissionCreatorForTest(
 #if BUILDFLAG(ENABLE_EXTENSIONS)
 void SupervisedUserService::AddOrUpdateExtensionApproval(
     const extensions::Extension& extension) {
+  if (!active_)
+    return;
   auto it = approved_extensions_map_.find(extension.id());
   bool has_key = it != approved_extensions_map_.end();
   ApprovedExtensionChange change_type = has_key
@@ -358,6 +360,8 @@ void SupervisedUserService::AddOrUpdateExtensionApproval(
 
 void SupervisedUserService::RemoveExtensionApproval(
     const extensions::Extension& extension) {
+  if (!active_)
+    return;
   UpdateApprovedExtension(extension.id(), extension.VersionString(),
                           ApprovedExtensionChange::kRemove);
 }