fido: wire up FidoChromeOSDiscovery behind a feature flag

Add the WebAuthenticationCrosPlatformAuthenticator feature flag (default
disabled). If enabled, it will cause the FidoChromeOSDiscovery to be
instantiated for MakeCredential and GetAssertion requests that permit
the 'internal' transport.

Also move ChromeOS code up into the device namespace like most of the
other fido-related code. Its naming is sufficiently unique.

Bug: b/144861739
Change-Id: I50bf39c5c7841a7358840968d10a568c6f22ae6d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2088535
Commit-Queue: Martin Kreichgauer <martinkr@google.com>
Reviewed-by: Adam Langley <agl@chromium.org>
Cr-Commit-Position: refs/heads/master@{#749331}

content/browser/webauth/authenticator_common.cc

@@ -472,6 +472,12 @@ bool IsUserVerifyingPlatformAuthenticatorAvailableImpl(
          device::WinWebAuthnApiAuthenticator::
              IsUserVerifyingPlatformAuthenticatorAvailable(
                  discovery_factory->win_webauthn_api());
+#elif defined(OS_CHROMEOS)
+  if (browser_context->IsOffTheRecord()) {
+    return false;
+  }
+  return base::FeatureList::IsEnabled(
+      device::kWebAuthCrosPlatformAuthenticator);
 #else
   return false;
 #endif

content/browser/webauth/authenticator_impl_unittest.cc

@@ -1703,7 +1703,7 @@ TEST_F(AuthenticatorImplTest, GetAssertionResponseWithAttestedCredentialData) {
 }
 
 #if defined(OS_WIN)
-TEST_F(AuthenticatorImplTest, WinIsUVPAA) {
+TEST_F(AuthenticatorImplTest, IsUVPAA) {
   device::FakeWinWebAuthnApi win_webauthn_api;
   auto discovery_factory =
       std::make_unique<device::test::FakeFidoDiscoveryFactory>();
@@ -1734,6 +1734,24 @@ TEST_F(AuthenticatorImplTest, WinIsUVPAA) {
 }
 #endif  // defined(OS_WIN)
 
+#if defined(OS_CHROMEOS)
+TEST_F(AuthenticatorImplTest, IsUVPAA) {
+  SimulateNavigation(GURL(kTestOrigin1));
+  for (const bool flag_enabled : {false, true}) {
+    SCOPED_TRACE(::testing::Message() << "flag_enabled=" << flag_enabled);
+    base::test::ScopedFeatureList scoped_feature_list;
+    scoped_feature_list.InitWithFeatureState(
+        device::kWebAuthCrosPlatformAuthenticator, flag_enabled);
+    mojo::Remote<blink::mojom::Authenticator> authenticator =
+        ConnectToAuthenticator();
+    TestIsUvpaaCallback cb;
+    authenticator->IsUserVerifyingPlatformAuthenticatorAvailable(cb.callback());
+    cb.WaitForCallback();
+    EXPECT_EQ(flag_enabled, cb.value());
+  }
+}
+#endif  // defined(OS_CHROMEOS)
+
 class OverrideRPIDAuthenticatorRequestDelegate
     : public AuthenticatorRequestClientDelegate {
  public:

device/fido/cros/authenticator.cc

@@ -21,8 +21,6 @@
 #include "third_party/cros_system_api/dbus/u2f/dbus-constants.h"
 
 namespace device {
-namespace fido {
-namespace cros {
 
 ChromeOSAuthenticator::ChromeOSAuthenticator() : weak_factory_(this) {}
 
@@ -269,6 +267,4 @@ base::WeakPtr<FidoAuthenticator> ChromeOSAuthenticator::GetWeakPtr() {
   return weak_factory_.GetWeakPtr();
 }
 
-}  // namespace cros
-}  // namespace fido
 }  // namespace device

device/fido/cros/authenticator.h

@@ -20,8 +20,6 @@
 #include "device/fido/fido_transport_protocol.h"
 
 namespace device {
-namespace fido {
-namespace cros {
 
 class COMPONENT_EXPORT(DEVICE_FIDO) ChromeOSAuthenticator
     : public FidoAuthenticator {
@@ -64,8 +62,6 @@ class COMPONENT_EXPORT(DEVICE_FIDO) ChromeOSAuthenticator
   base::WeakPtrFactory<ChromeOSAuthenticator> weak_factory_;
 };
 
-}  // namespace cros
-}  // namespace fido
 }  // namespace device
 
 #endif  // DEVICE_FIDO_CROS_AUTHENTICATOR_H_

device/fido/cros/discovery.cc

@@ -8,8 +8,6 @@
 #include "base/threading/sequenced_task_runner_handle.h"
 
 namespace device {
-namespace fido {
-namespace cros {
 
 FidoChromeOSDiscovery::FidoChromeOSDiscovery()
     : FidoDiscoveryBase(FidoTransportProtocol::kInternal),
@@ -37,6 +35,4 @@ void FidoChromeOSDiscovery::AddAuthenticator() {
   observer()->DiscoveryStarted(this, /*success=*/true, {authenticator_.get()});
 }
 
-}  // namespace cros
-}  // namespace fido
 }  // namespace device

device/fido/cros/discovery.h

@@ -13,8 +13,6 @@
 #include "device/fido/fido_discovery_base.h"
 
 namespace device {
-namespace fido {
-namespace cros {
 
 class COMPONENT_EXPORT(DEVICE_FIDO) FidoChromeOSDiscovery
     : public FidoDiscoveryBase {
@@ -32,8 +30,6 @@ class COMPONENT_EXPORT(DEVICE_FIDO) FidoChromeOSDiscovery
   base::WeakPtrFactory<FidoChromeOSDiscovery> weak_factory_;
 };
 
-}  // namespace cros
-}  // namespace fido
 }  // namespace device
 
 #endif  // DEVICE_FIDO_CROS_DISCOVERY_H_

device/fido/features.cc

@@ -28,4 +28,10 @@ const base::Feature kWebAuthCableLowLatency{"WebAuthenticationCableLowLatency",
                                             base::FEATURE_ENABLED_BY_DEFAULT};
 #endif  // defined(OS_CHROMEOS) || defined(OS_LINUX)
 
+#if defined(OS_CHROMEOS)
+const base::Feature kWebAuthCrosPlatformAuthenticator{
+    "WebAuthenticationCrosPlatformAuthenticator",
+    base::FEATURE_DISABLED_BY_DEFAULT};
+#endif  // defined(OS_CHROMEOS)
+
 }  // namespace device

device/fido/features.h

@@ -37,6 +37,12 @@ COMPONENT_EXPORT(DEVICE_FIDO)
 extern const base::Feature kWebAuthCableLowLatency;
 #endif  // defined(OS_CHROMEOS) || defined(OS_LINUX)
 
+#if defined(OS_CHROMEOS)
+// Enable a ChromeOS platform authenticator
+COMPONENT_EXPORT(DEVICE_FIDO)
+extern const base::Feature kWebAuthCrosPlatformAuthenticator;
+#endif  // defined(OS_CHROMEOS)
+
 }  // namespace device
 
 #endif  // DEVICE_FIDO_FEATURES_H_

device/fido/fido_discovery_factory.cc

@@ -25,6 +25,10 @@
 #include "device/fido/mac/discovery.h"
 #endif  // defined(OSMACOSX)
 
+#if defined(OS_CHROMEOS)
+#include "device/fido/cros/discovery.h"
+#endif  // defined(OS_CHROMEOS)
+
 namespace device {
 
 namespace {
@@ -68,14 +72,11 @@ std::unique_ptr<FidoDiscoveryBase> FidoDiscoveryFactory::Create(
       // TODO(https://crbug.com/825949): Add NFC support.
       return nullptr;
     case FidoTransportProtocol::kInternal:
-#if defined(OS_MACOSX)
-      return mac_touch_id_config_
-                 ? std::make_unique<fido::mac::FidoTouchIdDiscovery>(
-                       *mac_touch_id_config_)
-                 : nullptr;
+#if defined(OS_MACOSX) || defined(OS_CHROMEOS)
+      return MaybeCreatePlatformDiscovery();
 #else
       return nullptr;
-#endif  // defined(OS_MACOSX)
+#endif
   }
   NOTREACHED() << "Unhandled transport type";
   return nullptr;
@@ -117,6 +118,25 @@ FidoDiscoveryFactory::MaybeCreateWinWebAuthnApiDiscovery() {
 }
 #endif  // defined(OS_WIN)
 
+#if defined(OS_MACOSX)
+std::unique_ptr<FidoDiscoveryBase>
+FidoDiscoveryFactory::MaybeCreatePlatformDiscovery() const {
+  return mac_touch_id_config_
+             ? std::make_unique<fido::mac::FidoTouchIdDiscovery>(
+                   *mac_touch_id_config_)
+             : nullptr;
+}
+#endif
+
+#if defined(OS_CHROMEOS)
+std::unique_ptr<FidoDiscoveryBase>
+FidoDiscoveryFactory::MaybeCreatePlatformDiscovery() const {
+  return base::FeatureList::IsEnabled(kWebAuthCrosPlatformAuthenticator)
+             ? std::make_unique<FidoChromeOSDiscovery>()
+             : nullptr;
+}
+#endif
+
 FidoDiscoveryFactory::RequestState::RequestState() = default;
 FidoDiscoveryFactory::RequestState::~RequestState() = default;
 

device/fido/fido_discovery_factory.h

@@ -95,6 +95,10 @@ class COMPONENT_EXPORT(DEVICE_FIDO) FidoDiscoveryFactory {
         cable_pairing_callback_;
   };
 
+#if defined(OS_MACOSX) || defined(OS_CHROMEOS)
+  std::unique_ptr<FidoDiscoveryBase> MaybeCreatePlatformDiscovery() const;
+#endif
+
   RequestState request_state_;
 #if defined(OS_MACOSX)
   base::Optional<fido::mac::AuthenticatorConfig> mac_touch_id_config_;