Provide default splash screen style for Launcher and SystemUI.

Previous the splash screen style can either be EMPTY or ICON, and need
to be set by new hidden API #setSplashscreenStyle, so the flag will
always be "EMPTY" for those 3rd party Launcher Apps which may have not
upgrade to targetSDK 31.
To correct the default behaivor for Launcher Apps, create a new
UNDEFINED style as default value for splashScreenStyle, and if the
value is UNDEFINED, determine the style by checking the launch source.

Test: Verify no change when default home is NexusLauncher.
Test: Set 3rd-party Launcher as default home, verify the splash screen
style should be ICON style when launch app from Launcher.
Test: atest SplashscreenTests
Bug: 206746601

Change-Id: I105e2fcfc7a6ee8de7f442931cbeb4b6e517850d

core/java/android/app/ActivityOptions.java

@@ -431,7 +431,7 @@ public class ActivityOptions extends ComponentOptions {
     private boolean mOverrideTaskTransition;
     private String mSplashScreenThemeResName;
     @SplashScreen.SplashScreenStyle
-    private int mSplashScreenStyle;
+    private int mSplashScreenStyle = SplashScreen.SPLASH_SCREEN_STYLE_UNDEFINED;
     private boolean mRemoveWithTaskOrganizer;
     private boolean mLaunchedFromBubble;
     private boolean mTransientLaunch;

core/java/android/window/SplashScreen.java

@@ -42,6 +42,11 @@ import java.util.ArrayList;
  * <code>Activity.getSplashScreen()</code> to get the SplashScreen.</p>
  */
 public interface SplashScreen {
+    /**
+     * The splash screen style is not defined.
+     * @hide
+     */
+    int SPLASH_SCREEN_STYLE_UNDEFINED = -1;
     /**
      * Force splash screen to be empty.
      * @hide
@@ -55,6 +60,7 @@ public interface SplashScreen {
 
     /** @hide */
     @IntDef(prefix = { "SPLASH_SCREEN_STYLE_" }, value = {
+            SPLASH_SCREEN_STYLE_UNDEFINED,
             SPLASH_SCREEN_STYLE_EMPTY,
             SPLASH_SCREEN_STYLE_ICON
     })

services/core/java/com/android/server/wm/ActivityRecord.java

@@ -6432,6 +6432,13 @@ final class ActivityRecord extends WindowToken implements WindowManagerService.A
             } else if (optionsStyle == SplashScreen.SPLASH_SCREEN_STYLE_ICON) {
                 return false;
             }
+            // Choose the default behavior for Launcher and SystemUI when the SplashScreen style is
+            // not specified in the ActivityOptions.
+            if (mLaunchSourceType == LAUNCH_SOURCE_TYPE_HOME) {
+                return false;
+            } else if (mLaunchSourceType == LAUNCH_SOURCE_TYPE_SYSTEMUI) {
+                return true;
+            }
         }
         if (sourceRecord == null) {
             sourceRecord = searchCandidateLaunchingActivity();
@@ -6441,11 +6448,11 @@ final class ActivityRecord extends WindowToken implements WindowManagerService.A
             return sourceRecord.mSplashScreenStyleEmpty;
         }
 
-        // If this activity was launched from a system surface for first start, never use an empty
+        // If this activity was launched from Launcher or System for first start, never use an
-        // splash screen. Need to check sourceRecord before in case this activity is launched from
+        // empty splash screen.
-        // service.
+        // Need to check sourceRecord before in case this activity is launched from service.
-        // Otherwise use empty.
+        return !startActivity || !(mLaunchSourceType == LAUNCH_SOURCE_TYPE_SYSTEM
-        return !startActivity || !launchedFromSystemSurface();
+                || mLaunchSourceType == LAUNCH_SOURCE_TYPE_HOME);
     }
 
     private int getSplashscreenTheme() {