[m103] fido: remove broken --webauthn-remote-desktop-support check

The remoteDesktopClientOverride extension is gated on a Blink feature.
The enabled state for this feature is tied to the
--webauthn-remote-desktop-support browser switch. The switch in turn can
be added automatically to the renderer process command line by turning
on the webauthn.remote_proxied_requests enterprise policy.

However, AuthenticatorCommon checks for the switch on the *browser*
command line when receiving a request with a remoteDesktopClientOverride
extension. Hence, if you simply enable the enterprise policy and make a
request with the extension, the browser doesn't find that flag and kills
the renderer.

The correct fix here is to also make the policy append the switch to
the browser command line. But that is a bit more involved, so in the
meantime just remove the check to unbreak things. The check isn't
security critical: Even if a popped renderer enabled the flag
unilaterally and tried to exercise the extension, the browser process
would still refuse any such request from an origin that isn't
authorized to use it. Origins can only be authorized via the enterprise
policy or via another browser-side command-line switch
(--webauthn-remote-proxied-requests-allowed-additional-origin).

(cherry picked from commit 9a420ed)

Bug: 1327438
Change-Id: I8cbe7b1a9c8c2a0cf1f26e2e026550175dabf32d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3652407
Reviewed-by: Adam Langley <agl@chromium.org>
Commit-Queue: Martin Kreichgauer <martinkr@google.com>
Cr-Original-Commit-Position: refs/heads/main@{#1005561}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3662002
Auto-Submit: Martin Kreichgauer <martinkr@google.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/branch-heads/5060@{#196}
Cr-Branched-From: b83393d-refs/heads/main@{#1002911}

content/browser/webauth/authenticator_common.cc

@@ -549,16 +549,6 @@ void AuthenticatorCommon::MakeCredential(
 
   BeginRequestTimeout(options->timeout);
 
-  if (options->remote_desktop_client_override) {
-    // WebAuthRequestSecurityChecker will validate whether use of the extension
-    // is authorized.
-    if (!base::CommandLine::ForCurrentProcess()->HasSwitch(
-            switches::kWebAuthRemoteDesktopSupport)) {
-      mojo::ReportBadMessage("--webauthn-remote-desktop-support not enabled");
-      return;
-    }
-  }
-
   WebAuthRequestSecurityChecker::RequestType request_type =
       options->is_payment_credential_creation
           ? WebAuthRequestSecurityChecker::RequestType::kMakePaymentCredential
@@ -866,16 +856,6 @@ void AuthenticatorCommon::GetAssertion(
   DCHECK(get_assertion_response_callback_.is_null());
   get_assertion_response_callback_ = std::move(callback);
 
-  if (options->remote_desktop_client_override) {
-    // WebAuthRequestSecurityChecker will validate whether use of the extension
-    // is authorized.
-    if (!base::CommandLine::ForCurrentProcess()->HasSwitch(
-            switches::kWebAuthRemoteDesktopSupport)) {
-      mojo::ReportBadMessage("--webauthn-remote-desktop-support not enabled");
-      return;
-    }
-  }
-
   if (!options->is_conditional) {
     BeginRequestTimeout(options->timeout);
   }