Refactor post requests, implement bot cancel/terminate

appengine/swarming/elements/res/imp/tasklist/task-list.html

Index: appengine/swarming/elements/res/imp/tasklist/task-list.html
diff --git a/appengine/swarming/elements/res/imp/tasklist/task-list.html b/appengine/swarming/elements/res/imp/tasklist/task-list.html
index 5be3c649271cb04061a61c5b53e877dad87250b7..1fd26648a84f7fdfb600ae9d1c851cd5c15234e6 100644
--- a/appengine/swarming/elements/res/imp/tasklist/task-list.html
+++ b/appengine/swarming/elements/res/imp/tasklist/task-list.html
@@ -332,25 +332,9 @@
         }
         var id = task.task_id
 
-        // Keep toast displayed until we hear back from the cancel.
-        this.$.toast.duration = 0;
         this.$.toast.text="Canceling task " + id;
-        this.$.toast.open();
         var url = "/_ah/api/swarming/v1/task/" + id +"/cancel";
-        sk.request("POST", url, undefined, this._auth_headers).then(function(response) {
-          this.$.toast.close();
-          this.$.toast.show({
-            text: "Request sent.  Response: "+response,
-            duration: 3000,
-          });
-        }.bind(this)).catch(function(reason) {
-          console.log("Cancellation failed", reason);
-          this.$.toast.close();
-          this.$.toast.show({
-            text: "Request failed.  Reason: "+reason,
-            duration: 3000,
-          });
-        }.bind(this));
+        this._postWithToast(url, this.$.toast, this._auth_headers);
       },
 
       _tag: function(task, col) {