More docs for license screens (#6954)

packages/flutter/lib/src/foundation/licenses.dart

@@ -251,6 +251,14 @@ class LicenseEntryWithLineBreaks extends LicenseEntry {
 /// The LICENSE files in each package can either consist of a single license, or
 /// can be in the format described above. In the latter case, each component
 /// license and list of package names is merged independently.
+///
+/// See also:
+///
+///  * [showAboutDialog], which shows a Material-style dialog with information
+///    about the application, including a button that shows a [LicensePage] that
+///    uses this API to select licenses to show.
+///  * [AboutDrawerItem], which is a widget to put in a [Drawer] which
+///    automatically calls [showAboutDialog].
 class LicenseRegistry {
   LicenseRegistry._();
 

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

@@ -27,11 +27,11 @@ import 'theme.dart';
 /// version, icon, and copyright in the appropriate fields.
 ///
 /// The about box will include a button that shows licenses for software used by
-/// the application.
+/// the application. The licenses shown are those returned by the
+/// [LicenseRegistry] API, which can be used to add more licenses to the list.
 ///
 /// If your application does not have a [Drawer], you should provide an
 /// affordance to call [showAboutDialog] or (at least) [showLicensePage].
-// TODO(ianh): Mention the API for registering more licenses once it exists.
 class AboutDrawerItem extends StatelessWidget {
   /// Creates a drawer item for showing an about box.
   ///
@@ -137,6 +137,9 @@ class AboutDrawerItem extends StatelessWidget {
 ///
 /// If you do not need an about box in your application, you should at least
 /// provide an affordance to call [showLicensePage].
+///
+/// The licenses shown on the [LicensePage] are those returned by the
+/// [LicenseRegistry] API, which can be used to add more licenses to the list.
 void showAboutDialog({
   @required BuildContext context,
   String applicationName,
@@ -167,7 +170,9 @@ void showAboutDialog({
 ///
 /// The [AboutDialog] shown by [showAboutDialog] includes a button that calls
 /// [showLicensePage].
-// TODO(ianh): Mention the API for registering more licenses once it exists.
+///
+/// The licenses shown on the [LicensePage] are those returned by the
+/// [LicenseRegistry] API, which can be used to add more licenses to the list.
 void showLicensePage({
   @required BuildContext context,
   String applicationName,
@@ -191,6 +196,15 @@ void showLicensePage({
 /// used by the application.
 ///
 /// To show an [AboutDialog], use [showAboutDialog].
+///
+/// If the application has a [Drawer], the [AboutDrawerItem] widget can make the
+/// process of showing an about dialog simpler.
+///
+/// The [AboutDialog] shown by [showAboutDialog] includes a button that calls
+/// [showLicensePage].
+///
+/// The licenses shown on the [LicensePage] are those returned by the
+/// [LicenseRegistry] API, which can be used to add more licenses to the list.
 class AboutDialog extends StatelessWidget {
   /// Creates an about box.
   ///
@@ -304,14 +318,21 @@ class AboutDialog extends StatelessWidget {
 /// A page that shows licenses for software used by the application.
 ///
 /// To show a [LicensePage], use [showLicensePage].
-// TODO(ianh): Mention the API for registering more licenses once it exists.
+///
+/// The [AboutDialog] shown by [showAboutDialog] and [AboutDrawerItem] includes
+/// a button that calls [showLicensePage].
+///
+/// The licenses shown on the [LicensePage] are those returned by the
+/// [LicenseRegistry] API, which can be used to add more licenses to the list.
 class LicensePage extends StatefulWidget {
   /// Creates a page that shows licenses for software used by the application.
   ///
   /// The arguments are all optional. The application name, if omitted, will be
   /// derived from the nearest [Title] widget. The version and legalese values
   /// default to the empty string.
-  // TODO(ianh): Mention the API for registering more licenses once it exists.
+  ///
+  /// The licenses shown on the [LicensePage] are those returned by the
+  /// [LicenseRegistry] API, which can be used to add more licenses to the list.
   const LicensePage({
     Key key,
     this.applicationName,