Remove MutableProfileOAuth2TokenService on iOS.

ios/public/test/fake_profile_oauth2_token_service_ios_provider.mm

Index: ios/public/test/fake_profile_oauth2_token_service_ios_provider.mm
diff --git a/ios/public/test/fake_profile_oauth2_token_service_ios_provider.mm b/ios/public/test/fake_profile_oauth2_token_service_ios_provider.mm
index e6ff73d085dad5e7ff976b2ea96b3ae1edc8fab3..492877319f382da37d8d665d03d79ad0028b6ef1 100644
--- a/ios/public/test/fake_profile_oauth2_token_service_ios_provider.mm
+++ b/ios/public/test/fake_profile_oauth2_token_service_ios_provider.mm
@@ -12,8 +12,7 @@
 namespace ios {
 
 FakeProfileOAuth2TokenServiceIOSProvider::
-    FakeProfileOAuth2TokenServiceIOSProvider()
-    : is_using_shared_authentication_(true) {}
+    FakeProfileOAuth2TokenServiceIOSProvider() {}
 
 FakeProfileOAuth2TokenServiceIOSProvider::
     ~FakeProfileOAuth2TokenServiceIOSProvider() {}
@@ -24,7 +23,6 @@ void FakeProfileOAuth2TokenServiceIOSProvider::GetAccessToken(
     const std::string& client_secret,
     const std::set<std::string>& scopes,
     const AccessTokenCallback& callback) {
-  DCHECK(is_using_shared_authentication_);
   requests_.push_back(AccessTokenRequest(account_id, callback));
 }
 
@@ -73,11 +71,6 @@ void FakeProfileOAuth2TokenServiceIOSProvider::
   requests_.clear();
 }
 
-bool FakeProfileOAuth2TokenServiceIOSProvider::IsUsingSharedAuthentication()
-    const {
-  return is_using_shared_authentication_;
-}
-
 void
 FakeProfileOAuth2TokenServiceIOSProvider::InitializeSharedAuthentication() {}