Bug 1945969 - part 4: simplify android implementation of RecvIsUVPAA. r=keeler

Differential Revision: https://phabricator.services.mozilla.com/D236884

dom/webauthn/WebAuthnTransactionParent.cpp

@@ -42,6 +42,8 @@ void WebAuthnTransactionParent::DisconnectTransaction() {
 mozilla::ipc::IPCResult WebAuthnTransactionParent::RecvRequestRegister(
     const WebAuthnMakeCredentialInfo& aTransactionInfo,
     RequestRegisterResolver&& aResolver) {
+  MOZ_ASSERT(NS_IsMainThread());
+
   if (!mWebAuthnService) {
     mWebAuthnService = do_GetService("@mozilla.org/webauthn/service;1");
     if (!mWebAuthnService) {
@@ -202,6 +204,8 @@ mozilla::ipc::IPCResult WebAuthnTransactionParent::RecvRequestRegister(
 mozilla::ipc::IPCResult WebAuthnTransactionParent::RecvRequestSign(
     const WebAuthnGetAssertionInfo& aTransactionInfo,
     RequestSignResolver&& aResolver) {
+  MOZ_ASSERT(NS_IsMainThread());
+
   if (!mWebAuthnService) {
     mWebAuthnService = do_GetService("@mozilla.org/webauthn/service;1");
     if (!mWebAuthnService) {
@@ -344,6 +348,8 @@ mozilla::ipc::IPCResult WebAuthnTransactionParent::RecvRequestSign(
 }
 
 mozilla::ipc::IPCResult WebAuthnTransactionParent::RecvRequestCancel() {
+  MOZ_ASSERT(NS_IsMainThread());
+
   if (mTransactionId.isNothing()) {
     return IPC_OK();
   }
@@ -354,6 +360,8 @@ mozilla::ipc::IPCResult WebAuthnTransactionParent::RecvRequestCancel() {
 
 mozilla::ipc::IPCResult WebAuthnTransactionParent::RecvRequestIsUVPAA(
     RequestIsUVPAAResolver&& aResolver) {
+  MOZ_ASSERT(NS_IsMainThread());
+
 #ifdef MOZ_WIDGET_ANDROID
   // Try the nsIWebAuthnService. If we're configured for tests we
   // will get a result. Otherwise we expect NS_ERROR_NOT_IMPLEMENTED.
@@ -374,23 +382,16 @@ mozilla::ipc::IPCResult WebAuthnTransactionParent::RecvRequestIsUVPAA(
   }
 
   // The GeckoView implementation of
-  // isUserVerifiyingPlatformAuthenticatorAvailable does not block, but we must
+  // isUserVerifiyingPlatformAuthenticatorAvailable dispatches the work to a
-  // call it on the main thread. It returns a MozPromise which we can ->Then to
+  // background thread and returns a MozPromise which we can ->Then to call
-  // call aResolver on the IPDL background thread.
+  // aResolver on the current thread.
-  //
-  // Bug 1550788: there is an unnecessary layer of dispatching here: ipdl ->
-  // main -> a background thread. Other platforms just do ipdl -> a background
-  // thread.
   nsCOMPtr<nsISerialEventTarget> target = GetCurrentSerialEventTarget();
-  nsCOMPtr<nsIRunnable> runnable(NS_NewRunnableFunction(
-      __func__, [target, resolver = std::move(aResolver)]() {
   auto result = java::WebAuthnTokenManager::
       WebAuthnIsUserVerifyingPlatformAuthenticatorAvailable();
   auto geckoResult = java::GeckoResult::LocalRef(std::move(result));
   MozPromise<bool, bool, false>::FromGeckoResult(geckoResult)
-            ->Then(
+      ->Then(target, __func__,
-                target, __func__,
+             [resolver = std::move(aResolver)](
-                [resolver](
                  const MozPromise<bool, bool, false>::ResolveOrRejectValue&
                      aValue) {
                if (aValue.IsResolve()) {
@@ -399,8 +400,6 @@ mozilla::ipc::IPCResult WebAuthnTransactionParent::RecvRequestIsUVPAA(
                  resolver(false);
                }
              });
-      }));
-  NS_DispatchToMainThread(runnable.forget());
   return IPC_OK();
 
 #else
@@ -433,6 +432,7 @@ mozilla::ipc::IPCResult WebAuthnTransactionParent::RecvRequestIsUVPAA(
 void WebAuthnTransactionParent::ActorDestroy(ActorDestroyReason aWhy) {
   // Called either by Send__delete__() in RecvDestroyMe() above, or when
   // the channel disconnects. Ensure the token manager forgets about us.
+  MOZ_ASSERT(NS_IsMainThread());
 
   if (mTransactionId.isSome()) {
     DisconnectTransaction();