Some fixes for black screen when pressing home button

Pressing home button sometimes involves a rotation (eg. when app is
running in landscape mode but launch is fixed portrait mode). This will
trigger a screen freeze, which clears the transition. We still need to
add the opening app to the opening list even if transition is unset,
otherwise it doesn't wait for app to draw first frame.

Also during rotation, app, launcher and wallpaper all get relaunched.
The transition can't start until the first frame on the new launcher
window comes back. We can't start it based on the draw state of the old
window, because the old window could get removed and readded shortly
after we start the transition, and it shows up as a black frame.

bug: 27391256
bug: 27295820
Change-Id: I346685076657eef209d0fab68f272e218b55e011
diff --git a/services/core/java/com/android/server/am/ActivityStack.java b/services/core/java/com/android/server/am/ActivityStack.java
index e50722a..39895ac5 100644
--- a/services/core/java/com/android/server/am/ActivityStack.java
+++ b/services/core/java/com/android/server/am/ActivityStack.java
@@ -1088,6 +1088,13 @@
         mStackSupervisor.ensureActivitiesVisibleLocked(null, 0, !PRESERVE_WINDOWS);
     }
 
+    final void activityResumedLocked(IBinder token) {
+        final ActivityRecord r = ActivityRecord.forTokenLocked(token);
+        if (DEBUG_SAVED_STATE) Slog.i(TAG_STATES, "Resumed activity; dropping state of: " + r);
+        r.icicle = null;
+        r.haveState = false;
+    }
+
     final void activityStoppedLocked(ActivityRecord r, Bundle icicle,
             PersistableBundle persistentState, CharSequence description) {
         if (r.state != ActivityState.STOPPING) {
@@ -4436,10 +4443,10 @@
                     "Moving to " + (andResume ? "RESUMED" : "PAUSED") + " Relaunching " + r
                     + " callers=" + Debug.getCallers(6));
             r.forceNewConfig = false;
+            mStackSupervisor.activityRelaunchingLocked(r);
             r.app.thread.scheduleRelaunchActivity(r.appToken, results, newIntents, changes,
                     !andResume, new Configuration(mService.mConfiguration),
                     new Configuration(r.task.mOverrideConfig), preserveWindow);
-            mStackSupervisor.activityRelaunchingLocked(r);
             // Note: don't need to call pauseIfSleepingLocked() here, because
             // the caller will only pass in 'andResume' if this activity is
             // currently resumed, which implies we aren't sleeping.