Fix XMPP late response.

remoting/webapp/base/js/fallback_signal_strategy.js

Index: remoting/webapp/base/js/fallback_signal_strategy.js
diff --git a/remoting/webapp/base/js/fallback_signal_strategy.js b/remoting/webapp/base/js/fallback_signal_strategy.js
index 68623ae8a695013e942b135491bc41e73ef6d56f..2f84f7fb2ad92567bb6f7e8516d383a6d835e69a 100644
--- a/remoting/webapp/base/js/fallback_signal_strategy.js
+++ b/remoting/webapp/base/js/fallback_signal_strategy.js
@@ -39,7 +39,7 @@ remoting.FallbackSignalStrategy = function(primary,
    * @private {number}
    * @const
    */
-  this.PRIMARY_CONNECT_TIMEOUT_MS_ = 10 * 1000;
+  this.PRIMARY_CONNECT_TIMEOUT_MS_ = 25 * 1000;

[Jamie, 2017/04/26 17:25:40]

Looking at the stats, there's a big spike in XMPP/SUCCEEDED_LATE logs around
20s. Since XMPP is a expected to be more reliable than WCS, delaying WCS to give
the XMPP connection longer to succeed seems like a good trade-off.

 
   /**
    * @enum {string}
@@ -231,6 +231,7 @@ remoting.FallbackSignalStrategy.prototype.onPrimaryStateChanged_ =
         this.updateProgress_(
             this.primary_,
             remoting.FallbackSignalStrategy.Progress.SUCCEEDED_LATE);
+        return;  // Don't notify the external callback
       }
       break;