Milo buildbot builder page: Add pagnation with cursors.

milo/appengine/buildbot/html.go

Index: milo/appengine/buildbot/html.go
diff --git a/milo/appengine/buildbot/html.go b/milo/appengine/buildbot/html.go
index bde2071bb83b558daf4c747bc75e9b41fda32f30..dedd5ccd30be75a4f793ce0cd7a9f5d6036016b2 100644
--- a/milo/appengine/buildbot/html.go
+++ b/milo/appengine/buildbot/html.go
@@ -9,6 +9,7 @@ import (
 	"net/http"
 	"strconv"
 
+	"github.com/luci/gae/service/datastore"
 	"github.com/luci/luci-go/milo/appengine/common"
 	"github.com/luci/luci-go/server/router"
 	"github.com/luci/luci-go/server/templates"
@@ -80,8 +81,19 @@ func BuilderHandler(c *router.Context) {
 	if limit < 0 {
 		limit = 25
 	}
+	sCursor := c.Request.FormValue("cursor")
 
-	result, err := builderImpl(c.Context, master, builder, limit)
+	var thisCursor *datastore.Cursor
+	if sCursor != "" {
+		tmpCur, err := datastore.DecodeCursor(c.Context, sCursor)
+		if err != nil {
+			common.ErrorPage(c, http.StatusBadRequest, fmt.Sprintf("bad cursor: %s", err.Error()))
+			return
+		}
+		thisCursor = &tmpCur
+	}
+
+	result, err := builderImpl(c.Context, master, builder, limit, thisCursor)
 	if err != nil {
 		common.ErrorPage(c, http.StatusInternalServerError, err.Error())
 		return