Refactor prior to adding task-page

appengine/swarming/elements/res/imp/botpage/bot-page-data.html

 <!--
   Copyright 2016 The LUCI Authors. All rights reserved.
   Use of this source code is governed under the Apache License, Version 2.0
   that can be found in the LICENSE file.
 
   This in an HTML Import-able file that contains the definition
   of the following elements:
 
     <bot-page-data>
 
   This makes calls authenticated with Oauth 2 to the swarming apis.  It parses
   that data into usable data structures.
 
   Properties:
-    busy: Boolean, if we are fetching any data from the server.
+    // input
+    auth_headers: Object, the OAuth2 header to include in the request.  This
+        should come from swarming-app.
+    bot_id: String, the id of the bot to fetch data on.
+    // output
     bot: Object, The information about the bot. See swarming_rpcs.py#BotInfo
         for all relevent fields.
+    busy: Boolean, if we are fetching any data from the server.
     events: Array<Object>, The most recent events that pertain to this bot.
         Contains the following fields: "event_type", "message", "ts" (timestamp),
         "quarantined", "version".
     tasks: Array<Object>, The most recent tasks done by this bot.
         Contains the following fields: "abandoned_ts", "bot_version", "duration",
         "failure", "internal_failure", "modified_ts", "name", "started_ts",
         "state", "task_id", "try_number".
 
   Methods:
     request(): Force a fetch of the data. This happens automatically when
@@ skipping 192 matching lines @@
         tasks.forEach(function(task){
           // Do any preprocessing here
           TASK_TIMES.forEach(function(time) {
             if (task[time]) {
               task[time] = new Date(task[time]);
               task["human_"+time] = formatDate(task[time]);
             }
           });
 
           if (task.duration) {
-            task.human_duration = sk.human.strDuration(task.duration) || "0s";
+            task.human_duration = this._humanDuration(task.duration);
           } else {
             var end = task.completed_ts || task.abandoned_ts || task.modified_ts || new Date();
             task.human_duration = this._timeDiffExact(task.started_ts, end);
           }
 
           task.state = task.state || "UNKNOWN";
           if (task.state === "COMPLETED") {
             if (task.failure) {
               task.state = "FAILURE";
             } else {
               task.state = "SUCCESS";
             }
           }
 
         }.bind(this));
 
         // Sort the most recent tasks first.
         tasks.sort(function(a,b) {
           return b.started_ts - a.started_ts;
         });
 
         return tasks;
       }
 
     });
   })();
   </script>
 </dom-module>