cmd/tailsca,java/comt/tailscale/ipn: don't require an Activity for Google sign-out

The GoogleSignIn.getClient has a version that only needs a Context, not an Activity.

Updates tailscale/tailscale#670

Signed-off-by: Elias Naur <mail@eliasnaur.com>

android/src/main/java/com/tailscale/ipn/App.java

@@ -27,6 +27,11 @@ import java.security.GeneralSecurityException;
 import androidx.security.crypto.EncryptedSharedPreferences;
 import androidx.security.crypto.MasterKey;
 
+import com.google.android.gms.auth.api.signin.GoogleSignIn;
+import com.google.android.gms.auth.api.signin.GoogleSignInAccount;
+import com.google.android.gms.auth.api.signin.GoogleSignInClient;
+import com.google.android.gms.auth.api.signin.GoogleSignInOptions;
+
 import org.gioui.Gio;
 
 public class App extends Application {
@@ -85,6 +90,13 @@ public class App extends Application {
 		);
 	}
 
+	void googleSignOut() {
+		GoogleSignInOptions gso = new GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
+			.build();
+		GoogleSignInClient client = GoogleSignIn.getClient(this, gso);
+		client.signOut();
+	}
+
 	void setTileStatus(boolean wantRunning) {
 		if (Build.VERSION.SDK_INT < Build.VERSION_CODES.N) {
 			return;

android/src/main/java/com/tailscale/ipn/Peer.java

@@ -58,13 +58,6 @@ public class Peer extends Fragment {
 		super.onDestroy();
 	}
 
-	public void googleSignOut() {
-		GoogleSignInOptions gso = new GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
-			.build();
-		GoogleSignInClient client = GoogleSignIn.getClient(getActivity(), gso);
-		client.signOut();
-	}
-
 	public void googleSignIn(String serverOAuthID) {
 		GoogleSignInOptions gso = new GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
 			.requestIdToken(serverOAuthID)

cmd/tailscale/main.go

@@ -670,7 +670,7 @@ func (a *App) processUIEvents(w *app.Window, events []UIEvent, peer jni.Object,
 			a.store.WriteString(loginMethodPrefKey, loginMethodWeb)
 			requestBackend(e)
 		case LogoutEvent:
-			a.signOut(peer)
+			a.signOut()
 			requestBackend(e)
 		case ConnectEvent:
 			requestBackend(e)
@@ -686,12 +686,9 @@ func (a *App) processUIEvents(w *app.Window, events []UIEvent, peer jni.Object,
 	}
 }
 
-func (a *App) signOut(peer jni.Object) {
-	if peer == 0 {
-		return
-	}
+func (a *App) signOut() {
 	err := jni.Do(a.jvm, func(env jni.Env) error {
-		return a.callVoidMethod(peer, "googleSignOut", "()V")
+		return a.callVoidMethod(a.appCtx, "googleSignOut", "()V")
 	})
 	if err != nil {
 		fatalErr(err)