Add Teamfood flag enabling Predictive Back at runtime.

Bug: 255854141
Test: Passed presubmit
Change-Id: I6add68a4f9e68136d82c38502825d02cdfb70bf0

packages/SystemUI/src/com/android/systemui/flags/Flags.kt

@@ -372,6 +372,11 @@ object Flags {
     @JvmField
     val NEW_BACK_AFFORDANCE = unreleasedFlag(1203, "new_back_affordance", teamfood = false)
 
+    // TODO(b/255854141): Tracking Bug
+    @JvmField
+    val WM_ENABLE_PREDICTIVE_BACK_SYSUI =
+        unreleasedFlag(1204, "persist.wm.debug.predictive_back_sysui_enable", teamfood = false)
+
     // 1300 - screenshots
     // TODO(b/254512719): Tracking Bug
     @JvmField val SCREENSHOT_REQUEST_PROCESSOR = releasedFlag(1300, "screenshot_request_processor")

packages/SystemUI/src/com/android/systemui/statusbar/phone/CentralSurfacesImpl.java

@@ -994,6 +994,11 @@ public class CentralSurfacesImpl implements CoreStartable, CentralSurfaces {
         // Lastly, call to the icon policy to install/update all the icons.
         mIconPolicy.init();
 
+        // Based on teamfood flag, turn predictive back dispatch on at runtime.
+        if (mFeatureFlags.isEnabled(Flags.WM_ENABLE_PREDICTIVE_BACK_SYSUI)) {
+            mContext.getApplicationInfo().setEnableOnBackInvokedCallback(true);
+        }
+
         mKeyguardStateController.addCallback(new KeyguardStateController.Callback() {
             @Override
             public void onUnlockedChanged() {

packages/SystemUI/tests/src/com/android/systemui/controls/management/ControlsFavoritingActivityTest.kt

@@ -5,6 +5,7 @@ import android.testing.AndroidTestingRunner
 import android.testing.TestableLooper
 import android.window.OnBackInvokedCallback
 import android.window.OnBackInvokedDispatcher
+import androidx.test.filters.FlakyTest
 import androidx.test.filters.SmallTest
 import androidx.test.rule.ActivityTestRule
 import androidx.test.runner.intercepting.SingleActivityFactory
@@ -79,6 +80,8 @@ class ControlsFavoritingActivityTest : SysuiTestCase() {
         activityRule.launchActivity(intent)
     }
 
+    // b/259549854 to root-cause and fix
+    @FlakyTest
     @Test
     fun testBackCallbackRegistrationAndUnregistration() {
         // 1. ensure that launching the activity results in it registering a callback