Fix Security Key proxying.

Gnubby was added a a Capbility in https://codereview.chromium.org/787033003,
but since it is not negotiated between host and client, that's not the right
way to make it configurable.

BUG=448131

Review URL: https://codereview.chromium.org/878573006

Cr-Commit-Position: refs/heads/master@{#313181}

remoting/webapp/crd/js/client_session.js

@@ -408,10 +408,6 @@ remoting.ClientSession.Capability = {
   // Indicates that the client supports 'cast'ing the video stream to a
   // cast-enabled device.
   CAST: 'casting',
-
-  // When enabled, this capability results in the client informing the host
-  // that it supports Gnubby-based authentication.
-  GNUBBY_AUTH: 'gnubbyAuth'
 };
 
 /**
@@ -1572,8 +1568,7 @@ remoting.ClientSession.prototype.processGnubbyAuthMessage_ = function(data) {
  * @private
  */
 remoting.ClientSession.prototype.createGnubbyAuthHandler_ = function() {
-  if (this.hasCapability_(remoting.ClientSession.Capability.GNUBBY_AUTH) &&
-      this.mode_ == remoting.ClientSession.Mode.ME2ME) {
+  if (this.mode_ == remoting.ClientSession.Mode.ME2ME) {
     this.gnubbyAuthHandler_ = new remoting.GnubbyAuthHandler(this);
     // TODO(psj): Move to more generic capabilities mechanism.
     this.sendGnubbyAuthMessage({'type': 'control', 'option': 'auth-v1'});

remoting/webapp/crd/js/desktop_remoting.js

@@ -138,8 +138,7 @@ remoting.DesktopRemoting.prototype.getRequiredCapabilities = function() {
     remoting.ClientSession.Capability.VIDEO_RECORDER,
     // TODO(aiguha): Add this capability based on a gyp/command-line flag,
     // rather than by default.
-    remoting.ClientSession.Capability.CAST,
-    remoting.ClientSession.Capability.GNUBBY_AUTH
+    remoting.ClientSession.Capability.CAST
   ];
 };