Cleanup background activity starts for release.

This removes the parts of the feature that were only needed in beta
releases:
- Toast when a start is or would be blocked.
- Configurable whitelist of exempt apps.
- Global setting to disable.

Not to be submitted until after beta 5 is cut.

Bug: 131747138
Test: atest BackgroundActivityLaunchTest
Test: atest RootWindowContainerTests
Test: atest WmTests:ActivityStarterTests
Test: atest CtsWindowManagerDeviceTestCases:ActivityStarterTests
Test: atest CtsAppTestCases:.ServiceTest

Change-Id: I3d8b9c72c8fac86b93ac57a8a1988f4133043af8
diff --git a/services/core/java/com/android/server/wm/ActivityTaskManagerService.java b/services/core/java/com/android/server/wm/ActivityTaskManagerService.java
index 7863756..ea86f29 100644
--- a/services/core/java/com/android/server/wm/ActivityTaskManagerService.java
+++ b/services/core/java/com/android/server/wm/ActivityTaskManagerService.java
@@ -2393,9 +2393,7 @@
                 null /* intent */, "moveTaskToFront");
         if (starter.shouldAbortBackgroundActivityStart(callingUid, callingPid, callingPackage, -1,
                 -1, callerApp, null, false, null)) {
-            boolean abort = !isBackgroundActivityStartsEnabled();
-            starter.showBackgroundActivityBlockedToast(abort, callingPackage);
-            if (abort) {
+            if (!isBackgroundActivityStartsEnabled()) {
                 return;
             }
         }
@@ -5426,13 +5424,6 @@
         return mAmInternal.isBackgroundActivityStartsEnabled();
     }
 
-    boolean isPackageNameWhitelistedForBgActivityStarts(@Nullable String packageName) {
-        if (packageName == null) {
-            return false;
-        }
-        return mAmInternal.isPackageNameWhitelistedForBgActivityStarts(packageName);
-    }
-
     void enableScreenAfterBoot(boolean booted) {
         EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_ENABLE_SCREEN,
                 SystemClock.uptimeMillis());