mdm: define OnboardingFlow syspolicy on Android (tailscale#648)

Adds an MDM setting `OnboardingFlow` which allows for the intro screen to be skipped when set to true.

Adds MDM Setting update to the top of MainActivity onCreate to ensure the latest MDMSettings are accurate. When attempting to do this while
relying on MDMSettings being update during onResume it created a race condition where occasionally OnboardingFlow was being evaluated to the
default value `show` when in reality it should be set to `hide`.

updates tailscale/corp#29482

Signed-off-by: zbuchheit <zachb@tailscale.com>

Author: zbuchheit

android/src/main/java/com/tailscale/ipn/MainActivity.kt

@@ -49,6 +49,7 @@ import androidx.navigation.compose.composable
 import androidx.navigation.compose.rememberNavController
 import androidx.navigation.navArgument
 import com.tailscale.ipn.mdm.MDMSettings
+import com.tailscale.ipn.mdm.ShowHide
 import com.tailscale.ipn.ui.model.Ipn
 import com.tailscale.ipn.ui.notifier.Notifier
 import com.tailscale.ipn.ui.theme.AppTheme
@@ -133,6 +134,9 @@ class MainActivity : ComponentActivity() {
     App.get()
     vpnViewModel = ViewModelProvider(App.get()).get(VpnViewModel::class.java)
 
+    val rm = getSystemService(Context.RESTRICTIONS_SERVICE) as RestrictionsManager
+    MDMSettings.update(App.get(), rm)
+
     // (jonathan) TODO: Force the app to be portrait on small screens until we have
     // proper landscape layout support
     if (!isLandscapeCapable()) {
@@ -363,9 +367,7 @@ class MainActivity : ComponentActivity() {
                         onNavigateHome = backTo("main"), backTo("userSwitcher"))
                   }
                 }
-
-            // Show the intro screen one time
-            if (!introScreenViewed()) {
+            if (shouldDisplayOnboarding()) {
               navController.navigate("intro")
               setIntroScreenViewed(true)
             }
@@ -523,8 +525,11 @@ class MainActivity : ComponentActivity() {
     startActivity(intent)
   }
 
-  private fun introScreenViewed(): Boolean {
-    return getSharedPreferences("introScreen", Context.MODE_PRIVATE).getBoolean("seen", false)
+  private fun shouldDisplayOnboarding(): Boolean {
+    val onboardingFlowShowHide = MDMSettings.onboardingFlow.flow.value.value
+    val introSeen =
+        getSharedPreferences("introScreen", Context.MODE_PRIVATE).getBoolean("seen", false)
+    return (onboardingFlowShowHide == ShowHide.Show && !introSeen)
   }
 
   private fun setIntroScreenViewed(seen: Boolean) {

android/src/main/java/com/tailscale/ipn/mdm/MDMSettings.kt

@@ -101,6 +101,9 @@ object MDMSettings {
   // Overrides the value provided by os.Hostname() in Go
   val hostname = StringMDMSetting("Hostname", "Device Hostname")
 
+  // Allows admins to skip the get started intro screen
+  val onboardingFlow = ShowHideMDMSetting("OnboardingFlow", "Suppress the intro screen")
+
   val allSettings by lazy {
     MDMSettings::class
         .declaredMemberProperties

android/src/main/res/values/strings.xml

@@ -220,6 +220,8 @@
     <string name="run_as_exit_node_visibility">Run as exit node visibility</string>
     <string name="defines_an_auth_key_that_will_be_used_for_login">Defines an auth key that will be used for login.</string>
     <string name="auth_key">Auth Key</string>
+    <string name="skips_the_intro_page_shown_to_users_that_open_the_app_for_the_first_time">Skips the intro page shown to users that open the app for the first time</string>
+    <string name="onboarding_flow">Skip the Onboarding Flow</string>
 
     <!-- Permissions Management -->
     <string name="permissions">Permissions</string>

android/src/main/res/xml/app_restrictions.xml

@@ -140,4 +140,12 @@
         android:key="Hostname"
         android:restrictionType="string"
         android:title="@string/hostname" />
+
+    <restriction
+        android:description="@string/skips_the_intro_page_shown_to_users_that_open_the_app_for_the_first_time"
+        android:entries="@array/show_hide_labels"
+        android:entryValues="@array/show_hide"
+        android:key="OnboardingFlow"
+        android:restrictionType="choice"
+        android:title="@string/onboarding_flow" />
 </restrictions>