[iOS] ChromeAccountManagerService: rename pref_service_ -> local_state_

The name "pref_service" is typically understood to refer to the
*profile* pref service, but ChromeAccountManagerService actually uses
the *local state* pref service.

While we're here, this also adds a CHECK_IS_TEST() to ensure the pref
service can only be null in tests.

Bug: none
Change-Id: I1e290bc810477c25f3c7fce36082ffb51921b068
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5964924
Code-Coverage: findit-for-me@appspot.gserviceaccount.com <findit-for-me@appspot.gserviceaccount.com>
Reviewed-by: Jérôme Lebel <jlebel@chromium.org>
Commit-Queue: Marc Treib <treib@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1374582}

ios/chrome/browser/signin/model/chrome_account_manager_service.h

@@ -61,7 +61,7 @@ class ChromeAccountManagerService : public KeyedService,
 
   // Initializes the service, getting identities corresponding to `profile_name`
   // from the AccountProfileMapper.
-  ChromeAccountManagerService(PrefService* pref_service,
+  ChromeAccountManagerService(PrefService* local_state,
                               std::string_view profile_name);
   ChromeAccountManagerService(const ChromeAccountManagerService&) = delete;
   ChromeAccountManagerService& operator=(const ChromeAccountManagerService&) =
@@ -116,16 +116,16 @@ class ChromeAccountManagerService : public KeyedService,
       id<RefreshAccessTokenError> error) override;
 
  private:
-  // Updates PatternAccountRestriction with the current `pref_service_`. If
-  // `pref_service_` is null, no identity will be filtered.
+  // Updates PatternAccountRestriction with the current `local_state_`. If
+  // `local_state_` is null, no identity will be filtered.
   void UpdateRestriction();
 
   // Returns a ResizedAvatarCache based on `avatar_size`.
   ResizedAvatarCache* GetAvatarCacheForIdentityAvatarSize(
       IdentityAvatarSize avatar_size);
 
-  // Used to retrieve restricted patterns.
-  raw_ptr<PrefService> pref_service_ = nullptr;
+  // The local-state pref service, used to retrieve restricted patterns.
+  raw_ptr<PrefService> local_state_ = nullptr;
   // Used to filter ChromeIdentities.
   PatternAccountRestriction restriction_;
   // Used to listen pref change.

ios/chrome/browser/signin/model/chrome_account_manager_service.mm

@@ -7,6 +7,7 @@
 #import <string_view>
 
 #import "base/check.h"
+#import "base/check_is_test.h"
 #import "base/memory/raw_ref.h"
 #import "base/strings/sys_string_conversions.h"
 #import "components/prefs/pref_service.h"
@@ -166,21 +167,24 @@ typename Collector::ResultType IterateOverIdentities(
 
 // Returns the PatternAccountRestriction according to the given PrefService.
 PatternAccountRestriction PatternAccountRestrictionFromPreference(
-    PrefService* pref_service) {
+    PrefService* local_state) {
   return PatternAccountRestrictionFromValue(
-      pref_service->GetList(prefs::kRestrictAccountsToPatterns));
+      local_state->GetList(prefs::kRestrictAccountsToPatterns));
 }
 
 }  // anonymous namespace.
 
 ChromeAccountManagerService::ChromeAccountManagerService(
-    PrefService* pref_service,
+    PrefService* local_state,
     std::string_view profile_name)
-    : pref_service_(pref_service), profile_name_(profile_name) {
-  // pref_service is null in test environment. In prod environment pref_service
-  // comes from GetApplicationContext()->GetLocalState() and couldn't be null.
-  if (pref_service_) {
-    registrar_.Init(pref_service_);
+    : local_state_(local_state), profile_name_(profile_name) {
+  // `local_state_` may be null in a test environment. In the prod environment,
+  // `local_state_` comes from GetApplicationContext()->GetLocalState() and
+  // couldn't be null.
+  if (!local_state_) {
+    CHECK_IS_TEST();
+  } else {
+    registrar_.Init(local_state_);
     registrar_.Add(
         prefs::kRestrictAccountsToPatterns,
         base::BindRepeating(&ChromeAccountManagerService::UpdateRestriction,
@@ -267,9 +271,9 @@ void ChromeAccountManagerService::Shutdown() {
   for (auto& observer : observer_list_) {
     observer.OnChromeAccountManagerServiceShutdown(this);
   }
-  if (pref_service_) {
+  if (local_state_) {
     registrar_.RemoveAll();
-    pref_service_ = nullptr;
+    local_state_ = nullptr;
   }
 }
 
@@ -309,7 +313,7 @@ void ChromeAccountManagerService::OnIdentityAccessTokenRefreshFailed(
 }
 
 void ChromeAccountManagerService::UpdateRestriction() {
-  restriction_ = PatternAccountRestrictionFromPreference(pref_service_);
+  restriction_ = PatternAccountRestrictionFromPreference(local_state_);
   OnIdentityListChanged();
 }