Add links to MP and resolve minor fixes

appengine/swarming/elements/res/imp/tasklist/task-list.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:
 
     <task-list>
 
@@ skipping 230 matching lines @@
         <paper-button dialog-dismiss autofocus>No</paper-button>
         <paper-button dialog-confirm>Yes</paper-button>
       </div>
     </paper-dialog>
 
     <error-toast></error-toast>
 
   </template>
   <script>
   (function(){
-    var specialColumns = ["deduped_from", "name", "state", "bot"];
+    var specialColumns = ["deduped_from", "name", "state", "bot", "sk_revision"];

[M-A Ruel, 2016/10/12 19:35:07]

This is still very one off. I would have preferred something even more generic.
I understand that this means going back and changing the tag associated to the
tasks. So my take is to:
- Decide for a generic tag name to designate the root commit URL and the commit
hash.
- In addition to this one, add the other one with a more generic name.
- Migrate task triggering to use the new tag.
- Remove sk_ specific code in there.

Same for sk_repo below.

While the above can be done in a follow up, please update
https://github.com/luci/luci-py/blob/master/appengine/swarming/doc/Magic-Valu...
in this CL with information about the special parsing of this tag.

[kjlubick, 2016/10/12 20:02:38]

I can take care of it in this CL and update our swarming task scheduler later. 
Magic Values have been added as source_revision and source_repo.

 
     // Given a time attribute like "abandoned_ts", humanTime returns a function
     // that returns the human-friendly version of that attribute. The human
     // friendly time was created in task-list-data.
     function humanTime(attr) {
       return function(task) {
         return this._attribute(task, "human_" + attr)[0];
       }
     }
     var columnMap = {
@@ skipping 155 matching lines @@
       reload: function() {
         if (!this._auth_headers || !this._query_params) {
           return;
         }
         var url = "/_ah/api/swarming/v1/tasks/list?" + sk.query.fromParamSet(this._query_params);
         this.$.page_tasks.load(url,this._auth_headers);
       },
 
       _skLink: function(task) {
         var r = this._attribute(task, "sk_revision")[0];
-        if (r === "none") {
+        var repo = this._attribute(task, "sk_repo")[0];
+        if (r === "none" || repo === "none") {
           return false;
         }
-        return "https://skia.googlesource.com/skia/+/" + r;
+        return repo + "/+/"+ r;

[M-A Ruel, 2016/10/12 19:35:07]

This is completely GoB specific. I'd like something that would work with
arbitrary git hosting service, e.g. github.

[kjlubick, 2016/10/12 20:02:38]

Done.  Like the other things, it's a "replace %s with the thing you want"

       },
 
       _tag: function(task, col) {
         if (!task || !task.tagMap) {
           return undefined;
         }
         return task.tagMap[col];
       },
 
       _taskClass: function(task) {
         return this.stateClass(this._column("state", task));
       }
     });
   })();
   </script>
 </dom-module>