Fix #9003 Make DrawerHeader margin configurable (#9006)

packages/flutter/lib/src/material/drawer_header.dart

@@ -31,6 +31,7 @@ class DrawerHeader extends StatelessWidget {
   const DrawerHeader({
     Key key,
     this.decoration,
+    this.margin: const EdgeInsets.only(bottom: 8.0),
     this.padding: const EdgeInsets.fromLTRB(16.0, 16.0, 16.0, 8.0),
     this.duration: const Duration(milliseconds: 250),
     this.curve: Curves.fastOutSlowIn,
@@ -53,6 +54,9 @@ class DrawerHeader extends StatelessWidget {
   /// If the child is null, the padding has no effect.
   final EdgeInsets padding;
 
+  /// The margin around the drawer header.
+  final EdgeInsets margin;
+
   /// The duration for animations of the [decoration].
   final Duration duration;
 
@@ -72,7 +76,7 @@ class DrawerHeader extends StatelessWidget {
     final double statusBarHeight = MediaQuery.of(context).padding.top;
     return new Container(
       height: statusBarHeight + _kDrawerHeaderHeight,
-      margin: const EdgeInsets.only(bottom: 8.0),
+      margin: margin,
       decoration: new BoxDecoration(
         border: new Border(
           bottom: new BorderSide(

packages/flutter/lib/src/material/user_accounts_drawer_header.dart

@@ -135,6 +135,7 @@ class UserAccountsDrawerHeader extends StatefulWidget {
   UserAccountsDrawerHeader({
     Key key,
     this.decoration,
+    this.margin: const EdgeInsets.only(bottom: 8.0),
     this.currentAccountPicture,
     this.otherAccountsPictures,
     @required this.accountName,
@@ -146,6 +147,9 @@ class UserAccountsDrawerHeader extends StatefulWidget {
   /// with its background color set to the current theme's primaryColor is used.
   final Decoration decoration;
 
+  /// The margin around the drawer header.
+  final EdgeInsets margin;
+
   /// A widget placed in the upper-left corner that represents the current
   /// user's account. Normally a [CircleAvatar].
   final Widget currentAccountPicture;
@@ -181,6 +185,7 @@ class _UserAccountsDrawerHeaderState extends State<UserAccountsDrawerHeader> {
       decoration: config.decoration ?? new BoxDecoration(
         backgroundColor: Theme.of(context).primaryColor,
       ),
+      margin: config.margin,
       child: new Column(
         crossAxisAlignment: CrossAxisAlignment.stretch,
         children: <Widget>[

packages/flutter/test/material/user_accounts_drawer_header_test.dart

@@ -14,31 +14,33 @@ void main() {
 
     await tester.pumpWidget(
       new Material(
-        child: new UserAccountsDrawerHeader(
-          currentAccountPicture: new CircleAvatar(
-            key: avatarA,
-            child: new Text('A')
+        child: new Center(
+          child: new UserAccountsDrawerHeader(
+            currentAccountPicture: new CircleAvatar(
+              key: avatarA,
+              child: new Text('A'),
+            ),
+            otherAccountsPictures: <Widget>[
+              new CircleAvatar(
+                child: new Text('B'),
+              ),
+              new CircleAvatar(
+                key: avatarC,
+                child: new Text('C'),
+              ),
+              new CircleAvatar(
+                key: avatarD,
+                child: new Text('D'),
+              ),
+              new CircleAvatar(
+                child: new Text('E'),
+              )
+            ],
+            accountName: new Text("name"),
+            accountEmail: new Text("email"),
           ),
-          otherAccountsPictures: <Widget>[
-            new CircleAvatar(
-              child: new Text('B')
-            ),
-            new CircleAvatar(
-              key: avatarC,
-              child: new Text('C')
-            ),
-            new CircleAvatar(
-              key: avatarD,
-              child: new Text('D')
-            ),
-            new CircleAvatar(
-              child: new Text('E')
-            )
-          ],
-          accountName: new Text("name"),
-          accountEmail: new Text("email")
-        )
-      )
+        ),
+      ),
     );
 
     expect(find.text('A'), findsOneWidget);
@@ -58,6 +60,9 @@ void main() {
     expect(box.size.width, equals(40.0));
     expect(box.size.height, equals(40.0));
 
+    box = tester.renderObject(find.byType(UserAccountsDrawerHeader));
+    expect(box.size.height, equals(160.0 + 8.0 + 1.0)); // height + bottom margin + bottom edge)
+
     final Point topLeft = tester.getTopLeft(find.byType(UserAccountsDrawerHeader));
     final Point topRight = tester.getTopRight(find.byType(UserAccountsDrawerHeader));
 
@@ -80,19 +85,25 @@ void main() {
       Widget accountName,
       Widget accountEmail,
       VoidCallback onDetailsPressed,
+      EdgeInsets margin,
     }) {
       return new Material(
-        child: new UserAccountsDrawerHeader(
-          currentAccountPicture: currentAccountPicture,
-          otherAccountsPictures: otherAccountsPictures,
-          accountName: accountName,
-          accountEmail: accountEmail,
-          onDetailsPressed: onDetailsPressed,
+        child: new Center(
+          child: new UserAccountsDrawerHeader(
+            currentAccountPicture: currentAccountPicture,
+            otherAccountsPictures: otherAccountsPictures,
+            accountName: accountName,
+            accountEmail: accountEmail,
+            onDetailsPressed: onDetailsPressed,
+            margin: margin,
+          ),
         ),
       );
     }
 
     await tester.pumpWidget(buildFrame());
+    final RenderBox box = tester.renderObject(find.byType(UserAccountsDrawerHeader));
+    expect(box.size.height, equals(160.0 + 1.0)); // height + bottom edge)
     expect(find.byType(Icon), findsNothing);
 
     await tester.pumpWidget(buildFrame(