feature/taildrop: move rest of Taildrop out of LocalBackend

Updates #12614

Change-Id: If451dec1d796f6a4216fe485975c87f0c62a53e5
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Co-authored-by: Nick Khyl <nickk@tailscale.com>

feature/taildrop/peerapi_test.go

@@ -50,19 +50,19 @@ func (h *peerAPIHandler) PeerCaps() tailcfg.PeerCapMap {
 	return nil
 }
 
-type fakeLocalBackend struct {
+type fakeExtension struct {
 	logf           logger.Logf
 	capFileSharing bool
 	clock          tstime.Clock
 	taildrop       *taildrop.Manager
 }
 
-func (lb *fakeLocalBackend) Clock() tstime.Clock { return lb.clock }
-func (lb *fakeLocalBackend) HasCapFileSharing() bool {
-	return lb.capFileSharing
+func (lb *fakeExtension) manager() *taildrop.Manager {
+	return lb.taildrop
 }
-func (lb *fakeLocalBackend) TaildropManager() (*taildrop.Manager, error) {
-	return lb.taildrop, nil
+func (lb *fakeExtension) Clock() tstime.Clock { return lb.clock }
+func (lb *fakeExtension) hasCapFileSharing() bool {
+	return lb.capFileSharing
 }
 
 type peerAPITestEnv struct {
@@ -472,16 +472,17 @@ func TestHandlePeerAPI(t *testing.T) {
 				selfNode.CapMap = tailcfg.NodeCapMap{tailcfg.CapabilityDebug: nil}
 			}
 			var rootDir string
-			var e peerAPITestEnv
 			if !tt.omitRoot {
 				rootDir = t.TempDir()
-				e.taildrop = taildrop.ManagerOptions{
-					Logf: e.logBuf.Logf,
-					Dir:  rootDir,
-				}.New()
 			}
 
-			lb := &fakeLocalBackend{
+			var e peerAPITestEnv
+			e.taildrop = taildrop.ManagerOptions{
+				Logf: e.logBuf.Logf,
+				Dir:  rootDir,
+			}.New()
+
+			ext := &fakeExtension{
 				logf:           e.logBuf.Logf,
 				capFileSharing: tt.capSharing,
 				clock:          &tstest.Clock{},
@@ -499,7 +500,7 @@ func TestHandlePeerAPI(t *testing.T) {
 				if req.Host == "example.com" {
 					req.Host = "100.100.100.101:12345"
 				}
-				handlePeerPutWithBackend(e.ph, lb, e.rr, req)
+				handlePeerPutWithBackend(e.ph, ext, e.rr, req)
 			}
 			for _, f := range tt.checks {
 				f(t, &e)
@@ -539,7 +540,7 @@ func TestFileDeleteRace(t *testing.T) {
 			Addresses: []netip.Prefix{netip.MustParsePrefix("100.100.100.101/32")},
 		}).View(),
 	}
-	fakeLB := &fakeLocalBackend{
+	fakeLB := &fakeExtension{
 		logf:           t.Logf,
 		capFileSharing: true,
 		clock:          &tstest.Clock{},