Make replaceLayers less flaky

This is done by checking for a splash screen layer before app layer becomes visible

Test: atest FlickerTest:OpenAppTransition#appLayerReplacesLauncher

Bug: 208623073
Change-Id: I2c1a84ddde363facce645d08bd09b66e69d16586

tests/FlickerTests/src/com/android/server/wm/flicker/CommonAssertions.kt

@@ -143,17 +143,26 @@ fun FlickerTestParameter.statusBarLayerRotatesScales() {
  * @param newLayer Layer that should be visible at the end
  * @param ignoreSnapshot If the snapshot layer should be ignored during the transition
  *     (useful mostly for app launch)
+ * @param ignoreSplashscreen If the splashscreen layer should be ignored during the transition.
+ *      If true then we will allow for a splashscreen to be shown before the layer is shown,
+ *      otherwise we won't and the layer must appear immediately.
  */
 fun FlickerTestParameter.replacesLayer(
     originalLayer: FlickerComponentName,
     newLayer: FlickerComponentName,
-    ignoreSnapshot: Boolean = false
+    ignoreSnapshot: Boolean = false,
+    ignoreSplashscreen: Boolean = true
 ) {
     assertLayers {
         val assertion = this.isVisible(originalLayer)
-        if (ignoreSnapshot) {
+        if (ignoreSnapshot || ignoreSplashscreen) {
             assertion.then()
-                    .isVisible(FlickerComponentName.SNAPSHOT, isOptional = true)
+        }
+        if (ignoreSnapshot) {
+            assertion.isVisible(FlickerComponentName.SNAPSHOT, isOptional = true)
+        }
+        if (ignoreSplashscreen) {
+            assertion.isSplashScreenVisibleFor(newLayer, isOptional = true)
         }
         assertion.then().isVisible(newLayer)
     }

tests/FlickerTests/src/com/android/server/wm/flicker/launch/OpenAppTransition.kt

@@ -166,7 +166,7 @@ abstract class OpenAppTransition(protected val testSpec: FlickerTestParameter) {
      * is replaced by [testApp], which remains visible until the end
      */
     open fun appLayerReplacesLauncher() {
-        testSpec.replacesLayer(LAUNCHER_COMPONENT, testApp.component)
+        testSpec.replacesLayer(LAUNCHER_COMPONENT, testApp.component, ignoreSnapshot = true)
     }
 
     /**