[CT] Update worker scripts to use new benchmarks and delete old benchmarks

ct/go/util/util.go

 // Utility that contains methods for both CT master and worker scripts.
 package util
 
 import (
         "bufio"
+        "encoding/json"
         "fmt"
         "io"
         "io/ioutil"
         "os"
         "path/filepath"
         "strconv"
         "sync"
         "time"
 
         "go.skia.org/infra/go/exec"
@@ skipping 214 matching lines @@
 // happening chrome zombie processes are periodically killed.
 func ChromeProcessesCleaner(locker sync.Locker, chromeCleanerTimer time.Duration) {
         for _ = range time.Tick(chromeCleanerTimer) {
                 glog.Info("The chromeProcessesCleaner goroutine has started")
                 glog.Info("Waiting for all existing tasks to complete before killing zombie chrome processes")
                 locker.Lock()
                 util.LogErr(ExecuteCmd("pkill", []string{"-9", "chrome"}, []string{}, PKILL_TIMEOUT, nil, nil))
                 locker.Unlock()
         }
 }
+
+// Contains the data included in CT pagesets.
+type PagesetVars struct {
+        // A comma separated list of URLs.
+        UrlsList string `json:"urls_list"`
+        // Will be either "mobile" or "desktop".
+        UserAgent string `json:"user_agent"`
+        // The location of the web page's WPR data file.
+        ArchiveDataFile string `json:"archive_data_file"`
+}
+
+func ReadPageset(pagesetPath string) (PagesetVars, error) {
+        decodedPageset := PagesetVars{}
+        pagesetContent, err := os.Open(pagesetPath)
+        if err != nil {
+                return decodedPageset, fmt.Errorf("Could not read %s: %s", pagesetPath, err)
+        }
+        if err := json.NewDecoder(pagesetContent).Decode(&decodedPageset); err != nil {
+                return decodedPageset, fmt.Errorf("Could not JSON decode %s: %s", pagesetPath, err)
+        }
+        return decodedPageset, nil
+}