[webauthn] Remove erroneous DCHECK

Do not DCHECK on
ChromeAuthenticatorRequestDelegate::DoesBlockRequestOnFailure if the
authenticator is nullptr. This situation could arise if the user e.g.
disconnects the authenticator while setting the pin.

Bug: 990136
Change-Id: Iea8c509ef7ae2d74feabbc7d8e66cde51a266a69
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1733023
Auto-Submit: Nina Satragno <nsatragno@chromium.org>
Commit-Queue: Ken Buchanan <kenrb@chromium.org>
Reviewed-by: Ken Buchanan <kenrb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#683696}

chrome/browser/webauthn/chrome_authenticator_request_delegate.cc

@@ -130,8 +130,6 @@ bool ChromeAuthenticatorRequestDelegate::DoesBlockRequestOnFailure(
   if (!weak_dialog_model_)
     return false;
 
-  DCHECK(authenticator || reason == InterestingFailureReason::kTimeout);
-
 #if defined(OS_WIN)
   if (authenticator && authenticator->IsWinNativeApiAuthenticator()) {
     // Do not display a Chrome error dialog if the user cancels out of the

chrome/browser/webauthn/chrome_authenticator_request_delegate_unittest.cc

@@ -86,6 +86,17 @@ TEST_F(ChromeAuthenticatorRequestDelegateTest,
   EXPECT_EQ(kTestPairedDeviceAddress2, second_address_value.GetString());
 }
 
+// Checks that DoesBlockRequestOnFailure does not crash if authenticator is
+// nullptr and reason is not kTimeout. Regression test for crbug.com/990136.
+TEST_F(ChromeAuthenticatorRequestDelegateTest,
+       DoesBlockRequestOnFailure__NullAuthenticator) {
+  ChromeAuthenticatorRequestDelegate delegate(main_rfh(), kRelyingPartyID);
+  EXPECT_TRUE(delegate.DoesBlockRequestOnFailure(
+      /*authenticator=*/nullptr,
+      ChromeAuthenticatorRequestDelegate::InterestingFailureReason::
+          kUserConsentDenied));
+}
+
 #if defined(OS_MACOSX)
 API_AVAILABLE(macos(10.12.2))
 std::string TouchIdMetadataSecret(