[Shrine] Adding outlines to text fields (#38895)

* Adding outlines to text fields

examples/flutter_gallery/lib/demo/shrine/login.dart

@@ -24,6 +24,12 @@ class LoginPage extends StatefulWidget {
 class _LoginPageState extends State<LoginPage> {
   final TextEditingController _usernameController = TextEditingController();
   final TextEditingController _passwordController = TextEditingController();
+  static const ShapeDecoration _decoration =  ShapeDecoration(
+    shape: BeveledRectangleBorder(
+      side: BorderSide(color: kShrineBrown900, width: 0.5),
+      borderRadius: BorderRadius.all(Radius.circular(7.0)),
+    ),
+  );
 
   @override
   Widget build(BuildContext context) {
@@ -61,20 +67,26 @@ class _LoginPageState extends State<LoginPage> {
             const SizedBox(height: 120.0),
             PrimaryColorOverride(
               color: kShrineBrown900,
-              child: TextField(
-                controller: _usernameController,
-                decoration: const InputDecoration(
-                  labelText: 'Username',
+              child: Container(
+                decoration: _decoration,
+                child: TextField(
+                  controller: _usernameController,
+                  decoration: const InputDecoration(
+                    labelText: 'Username',
+                  ),
                 ),
               ),
             ),
             const SizedBox(height: 12.0),
             PrimaryColorOverride(
               color: kShrineBrown900,
-              child: TextField(
-                controller: _passwordController,
-                decoration: const InputDecoration(
-                  labelText: 'Password',
+              child: Container(
+                decoration: _decoration,
+                child: TextField(
+                  controller: _passwordController,
+                  decoration: const InputDecoration(
+                    labelText: 'Password',
+                  ),
                 ),
               ),
             ),