mobile: Use new account API

mobile/lib/screens/email.dart

@@ -0,0 +1,102 @@
+import 'package:flutter/material.dart';
+import 'package:musicus_common/musicus_common.dart';
+
+class EmailScreen extends StatefulWidget {
+  final String email;
+
+  EmailScreen({
+    this.email,
+  });
+
+  @override
+  _EmailScreenState createState() => _EmailScreenState();
+}
+
+class _EmailScreenState extends State<EmailScreen> {
+  final _emailController = TextEditingController();
+
+  bool _loading = false;
+
+  @override
+  void initState() {
+    super.initState();
+
+    if (widget.email != null) {
+      _emailController.text = widget.email;
+    }
+  }
+
+  Future<void> _setEmail(String email) async {
+    setState(() {
+      _loading = true;
+    });
+
+    final backend = MusicusBackend.of(context);
+
+    await backend.client.updateAccount(
+      newEmail: email,
+    );
+
+    setState(() {
+      _loading = false;
+    });
+
+    Navigator.pop(context);
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(
+        title: Text('E-mail address'),
+        actions: <Widget>[
+          Builder(
+            builder: (context) {
+              if (_loading) {
+                return Padding(
+                  padding: const EdgeInsets.all(16.0),
+                  child: Center(
+                    child: SizedBox(
+                      width: 24.0,
+                      height: 24.0,
+                      child: CircularProgressIndicator(
+                        strokeWidth: 2.0,
+                      ),
+                    ),
+                  ),
+                );
+              } else {
+                return FlatButton(
+                  onPressed: () {
+                    _setEmail(_emailController.text);
+                  },
+                  child: Text('DONE'),
+                );
+              }
+            },
+          ),
+        ],
+      ),
+      body: ListView(
+        children: <Widget>[
+          Padding(
+            padding: const EdgeInsets.all(16.0),
+            child: TextField(
+              controller: _emailController,
+              keyboardType: TextInputType.emailAddress,
+              decoration: InputDecoration(
+                labelText: 'E-mail',
+              ),
+            ),
+          ),
+          ListTile(
+            title: Text('Delete E-mail address'),
+            onTap: () {
+              _setEmail('');
+            },
+          ),
+        ],
+      ),
+    );
+  }
+}