playground: Move context.T out of rpc.ServerCall.

The purpose of this change is to make our usage of context.T more
consistent; it was a bit lame that we gave guidance to never wrap
context.T in another type, but were doing it ourselves.  The JS
code is also being changed to follow this convention (in separate
CLs), so we'll be consistent between Go and JS as well.

The server implementation used to look like this:
func (*impl) Foo(call rpc.ServerCall, ...)

Now it looks like this:
func (*impl) Foo(ctx *context.T, call rpc.ServerCall, ...)

Also added a ServerCall.Security() function, which returns the
security.Call.  The security.Call is still embedded inside
context.T for now; a subsequent change will remove it from
context.T and add an explicit security.Call argument where
necessary.  That's a separate CL since some of the choices may be
more controversial, and it's a smaller set of changes.

MultiPart: 7/8
Change-Id: I230fc7a702cd4b976e8fd9d7ebbbf75b5edb2a5c
diff --git a/client/bundles/fortune/src/server/server.go b/client/bundles/fortune/src/server/server.go
index a7a204f..c90235d 100644
--- a/client/bundles/fortune/src/server/server.go
+++ b/client/bundles/fortune/src/server/server.go
@@ -12,6 +12,7 @@
 	"math/rand"
 
 	"v.io/v23"
+	"v.io/v23/context"
 	"v.io/v23/rpc"
 	"v.io/x/lib/vlog"
 	"v.io/x/ref/lib/security/securityflag"
@@ -43,13 +44,13 @@
 }
 
 // Methods that get called by RPC requests.
-func (f *fortuned) GetRandomFortune(rpc.ServerCall) (Fortune string, err error) {
+func (f *fortuned) GetRandomFortune(*context.T, rpc.ServerCall) (Fortune string, err error) {
 	Fortune = f.fortunes[f.random.Intn(len(f.fortunes))]
 	fmt.Printf("Serving: %s\n", Fortune)
 	return Fortune, nil
 }
 
-func (f *fortuned) AddNewFortune(_ rpc.ServerCall, Fortune string) error {
+func (f *fortuned) AddNewFortune(_ *context.T, _ rpc.ServerCall, Fortune string) error {
 	fmt.Printf("Adding: %s\n", Fortune)
 	f.fortunes = append(f.fortunes, Fortune)
 	return nil
diff --git a/go/src/v.io/x/playground/compilerd/jobqueue/jobqueue_test.go b/go/src/v.io/x/playground/compilerd/jobqueue/jobqueue_test.go
index 7c882f5..0a17ab5 100644
--- a/go/src/v.io/x/playground/compilerd/jobqueue/jobqueue_test.go
+++ b/go/src/v.io/x/playground/compilerd/jobqueue/jobqueue_test.go
@@ -30,7 +30,7 @@
 	pgDir := os.ExpandEnv("${V23_ROOT}/release/projects/playground/go")
 
 	cmd := exec.Command("make", "builder")
-	cmd.Dir = path.Join(pgDir, "src", "playground")
+	cmd.Dir = path.Join(pgDir, "src", "v.io", "x", "playground")
 	if out, err := cmd.CombinedOutput(); err != nil {
 		fmt.Println("Error running 'make builder'")
 		fmt.Println(string(out))
diff --git a/go/src/v.io/x/playground/testdata/src/pong/pong.go b/go/src/v.io/x/playground/testdata/src/pong/pong.go
index 298fbc4..6e171ab 100644
--- a/go/src/v.io/x/playground/testdata/src/pong/pong.go
+++ b/go/src/v.io/x/playground/testdata/src/pong/pong.go
@@ -10,6 +10,7 @@
 	"fmt"
 
 	"v.io/v23"
+	"v.io/v23/context"
 	"v.io/v23/rpc"
 	"v.io/v23/security"
 	"v.io/x/lib/vlog"
@@ -21,8 +22,8 @@
 
 type pongd struct{}
 
-func (f *pongd) Ping(call rpc.ServerCall, message string) (result string, err error) {
-	remote, _ := security.RemoteBlessingNames(call.Context())
+func (f *pongd) Ping(ctx *context.T, _ rpc.ServerCall, message string) (result string, err error) {
+	remote, _ := security.RemoteBlessingNames(ctx)
 	fmt.Printf("%v: %q\n", remote, message)
 	return "PONG", nil
 }