playground: clean up imports, some lint errors, and deprecated calls

Change-Id: I80ab6fb80bc1c384e03824ff1caa9375b8426ac2
Reviewed-on: https://go-review.googlesource.com/64690
Run-TryBot: Andrew Bonventre <andybons@golang.org>
Reviewed-by: Chris Broadfoot <cbro@golang.org>
diff --git a/app/goplay/compile.go b/app/goplay/compile.go
index 499b505..4cdfa1c 100644
--- a/app/goplay/compile.go
+++ b/app/goplay/compile.go
@@ -9,11 +9,12 @@
 	"io"
 	"net/http"
 
-	"appengine"
-	"appengine/urlfetch"
+	"google.golang.org/appengine"
+	"google.golang.org/appengine/log"
+	"google.golang.org/appengine/urlfetch"
 )
 
-const runUrl = "http://golang.org/compile?output=json"
+const runURL = "http://golang.org/compile?output=json"
 
 func init() {
 	http.Handle("/compile", hstsHandler(compile))
@@ -35,14 +36,14 @@
 	c := appengine.NewContext(req)
 	client := urlfetch.Client(c)
 	defer req.Body.Close()
-	r, err := client.Post(runUrl, req.Header.Get("Content-type"), req.Body)
+	r, err := client.Post(runURL, req.Header.Get("Content-type"), req.Body)
 	if err != nil {
-		c.Errorf("making POST request:", err)
+		log.Errorf(c, "making POST request: %v", err)
 		return err
 	}
 	defer r.Body.Close()
 	if _, err := io.Copy(w, r.Body); err != nil {
-		c.Errorf("copying response Body:", err)
+		log.Errorf(c, "copying response Body: %v", err)
 		return err
 	}
 	return nil
diff --git a/app/goplay/edit.go b/app/goplay/edit.go
index 5af8b1f..e63d21f 100644
--- a/app/goplay/edit.go
+++ b/app/goplay/edit.go
@@ -10,8 +10,9 @@
 	"net/http"
 	"strings"
 
-	"appengine"
-	"appengine/datastore"
+	"google.golang.org/appengine"
+	"google.golang.org/appengine/datastore"
+	"google.golang.org/appengine/log"
 )
 
 const hostname = "play.golang.org"
@@ -52,7 +53,7 @@
 		err := datastore.Get(c, key, snip)
 		if err != nil {
 			if err != datastore.ErrNoSuchEntity {
-				c.Errorf("loading Snippet: %v", err)
+				log.Errorf(c, "loading Snippet: %v", err)
 			}
 			http.Error(w, "Snippet not found", http.StatusNotFound)
 			return
diff --git a/app/goplay/share.go b/app/goplay/share.go
index f02752d..cf8a772 100644
--- a/app/goplay/share.go
+++ b/app/goplay/share.go
@@ -12,8 +12,9 @@
 	"io"
 	"net/http"
 
-	"appengine"
-	"appengine/datastore"
+	"google.golang.org/appengine"
+	"google.golang.org/appengine/datastore"
+	"google.golang.org/appengine/log"
 )
 
 const salt = "[replace this with something unique]"
@@ -60,7 +61,7 @@
 	_, err := io.Copy(&body, io.LimitReader(r.Body, maxSnippetSize+1))
 	r.Body.Close()
 	if err != nil {
-		c.Errorf("reading Body: %v", err)
+		log.Errorf(c, "reading Body: %v", err)
 		http.Error(w, "Server Error", http.StatusInternalServerError)
 		return
 	}
@@ -74,7 +75,7 @@
 	key := datastore.NewKey(c, "Snippet", id, 0, nil)
 	_, err = datastore.Put(c, key, snip)
 	if err != nil {
-		c.Errorf("putting Snippet: %v", err)
+		log.Errorf(c, "putting Snippet: %v", err)
 		http.Error(w, "Server Error", http.StatusInternalServerError)
 		return
 	}