[signin] AccountReconcilorFactory uses the per-profile account consistency

The AccountReconcilorFactory was using the value from the Finch config
experiment instead of the per-profile value. This can lead to bugs when
these differ, which happens in particular when the client ID is not set.

Bug: 777774
Change-Id: I5c67ab704be119770d919a0ce3b8a623809ef0f2
Reviewed-on: https://chromium-review.googlesource.com/1097128
Commit-Queue: David Roger <droger@chromium.org>
Reviewed-by: Mihai Sardarescu <msarda@chromium.org>
Cr-Commit-Position: refs/heads/master@{#566808}

chrome/browser/signin/account_reconcilor_factory.cc

@@ -105,36 +105,32 @@ KeyedService* AccountReconcilorFactory::BuildServiceInstanceFor(
 // static
 std::unique_ptr<signin::AccountReconcilorDelegate>
 AccountReconcilorFactory::CreateAccountReconcilorDelegate(Profile* profile) {
-  if (AccountConsistencyModeManager::IsMirrorEnabledForProfile(profile)) {
+  signin::AccountConsistencyMethod account_consistency =
+      AccountConsistencyModeManager::GetMethodForProfile(profile);
+  switch (account_consistency) {
+    case signin::AccountConsistencyMethod::kMirror:
 #if defined(OS_CHROMEOS)
-    // Only for child accounts on Chrome OS, use the specialized Mirror
-    // delegate.
-    if (profile->IsChild()) {
-      return std::make_unique<ChromeOSChildAccountReconcilorDelegate>(
-          SigninManagerFactory::GetForProfile(profile));
-    }
+      // Only for child accounts on Chrome OS, use the specialized Mirror
+      // delegate.
+      if (profile->IsChild()) {
+        return std::make_unique<ChromeOSChildAccountReconcilorDelegate>(
+            SigninManagerFactory::GetForProfile(profile));
+      }
 #endif
-    return std::make_unique<signin::MirrorAccountReconcilorDelegate>(
-        SigninManagerFactory::GetForProfile(profile));
-  }
-  // TODO(droger): Remove this switch case. |AccountConsistencyModeManager| is
-  // the source of truth.
-  switch (signin::GetAccountConsistencyMethod()) {
-    case signin::AccountConsistencyMethod::kMirror:
-      // It is not possible for |IsMirrorEnabledForProfile| to return false,
-      // and this case being true.
-      NOTREACHED();
-      return nullptr;
+      return std::make_unique<signin::MirrorAccountReconcilorDelegate>(
+          SigninManagerFactory::GetForProfile(profile));
+
     case signin::AccountConsistencyMethod::kDisabled:
     case signin::AccountConsistencyMethod::kDiceFixAuthErrors:
       return std::make_unique<signin::AccountReconcilorDelegate>();
+
     case signin::AccountConsistencyMethod::kDicePrepareMigration:
     case signin::AccountConsistencyMethod::kDiceMigration:
     case signin::AccountConsistencyMethod::kDice:
 #if BUILDFLAG(ENABLE_DICE_SUPPORT)
       return std::make_unique<signin::DiceAccountReconcilorDelegate>(
           ChromeSigninClientFactory::GetForProfile(profile),
-          AccountConsistencyModeManager::GetMethodForProfile(profile));
+          account_consistency);
 #else
       NOTREACHED();
       return nullptr;