fido: fix a Touch ID assertion regression

CL:1800725 changed the way TouchIdAuthenticator was injected into the
FidoRequestHandlerBase. As a result, the code in GetAssertionRequestHandler
that was supposed to set
|transport_availability_info().has_recognized_mac_touch_id_credential| to
indicate to the UI whether it may dispatch a request to the Touch ID
authenticator or not was never executed. As a result, all GetAssertion
requests to Touch ID resulted in an immediate UI error.

To fix, unify the two code paths for adding authenticators in
FidoRequestHandlerBase.

Fixed: 1012500
Change-Id: I3e6a4e84892c1843f2ca2acd947eaf68269089f2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1850799Reviewed-by: Nina Satragno <nsatragno@chromium.org>
Commit-Queue: Martin Kreichgauer <martinkr@google.com>
Cr-Commit-Position: refs/heads/master@{#704702}

device/fido/fido_request_handler_base.cc

@@ -231,13 +231,6 @@ void FidoRequestHandlerBase::Start() {
     discovery->Start();
 }
 
-void FidoRequestHandlerBase::AuthenticatorAdded(
-    FidoDiscoveryBase* discovery,
-    FidoAuthenticator* authenticator) {
-  DCHECK(!base::Contains(active_authenticators(), authenticator->GetId()));
-  AddAuthenticator(authenticator);
-}
-
 void FidoRequestHandlerBase::AuthenticatorRemoved(
     FidoDiscoveryBase* discovery,
     FidoAuthenticator* authenticator) {
@@ -288,14 +281,15 @@ void FidoRequestHandlerBase::DiscoveryStarted(
     FidoDiscoveryBase* discovery,
     bool success,
     std::vector<FidoAuthenticator*> authenticators) {
-  for (auto* authenticator : authenticators)
-    AddAuthenticator(authenticator);
-
+  for (auto* authenticator : authenticators) {
+    AuthenticatorAdded(discovery, authenticator);
+  }
   DCHECK(notify_observer_callback_);
   notify_observer_callback_.Run();
 }
 
-void FidoRequestHandlerBase::AddAuthenticator(
+void FidoRequestHandlerBase::AuthenticatorAdded(
+    FidoDiscoveryBase* discovery,
     FidoAuthenticator* authenticator) {
   DCHECK(authenticator &&
          !base::Contains(active_authenticators(), authenticator->GetId()));

device/fido/fido_request_handler_base.h

@@ -262,7 +262,6 @@ class COMPONENT_EXPORT(DEVICE_FIDO) FidoRequestHandlerBase
       const base::flat_set<FidoTransportProtocol>& available_transports);
 #endif
 
-  void AddAuthenticator(FidoAuthenticator* authenticator);
   void NotifyObserverTransportAvailability();
 
   // Invokes FidoAuthenticator::InitializeAuthenticator(), followed by

device/fido/get_assertion_request_handler.cc

@@ -321,6 +321,9 @@ void GetAssertionRequestHandler::AuthenticatorAdded(
   DCHECK_CALLED_ON_VALID_SEQUENCE(my_sequence_checker_);
 
 #if defined(OS_MACOSX)
+  // Indicate to the UI whether a GetAssertion call to Touch ID would succeed
+  // or not. This needs to happen before the base AuthenticatorAdded()
+  // implementation runs |notify_observer_callback_| for this callback.
   if (authenticator->IsTouchIdAuthenticator()) {
     transport_availability_info().has_recognized_mac_touch_id_credential =
         static_cast<fido::mac::TouchIdAuthenticator*>(authenticator)