Use legacy import paths for Google stuff.
--- a/google/default.go
+++ b/google/default.go
@@ -14,7 +14,7 @@
 	"path/filepath"
 	"runtime"
 
-	"cloud.google.com/go/compute/metadata"
+	"google.golang.org/cloud/compute/metadata"
 	"golang.org/x/net/context"
 	"golang.org/x/oauth2"
 	"golang.org/x/oauth2/jwt"
--- a/google/google.go
+++ b/google/google.go
@@ -21,7 +21,7 @@
 	"strings"
 	"time"
 
-	"cloud.google.com/go/compute/metadata"
+	"google.golang.org/cloud/compute/metadata"
 	"golang.org/x/oauth2"
 	"golang.org/x/oauth2/jwt"
 )