Mark occluded home stack as invisible.

- The home stack is still visible when a translucent activity (like 
  dialer) is on top, which caused us to use the logic path that just 
  tries to launch the next task.  However, that path does not reload
  the stack state (since the activity stack generally doesn’t change
  while Recents is visible) so it was always launching the already top
  activity.  The new check ensures that we start the activity anew
  as if it was coming from an occluding app.

Bug: 28767764
Change-Id: Iec0fdc0957e5070cec532c5de5cba3454c906a3b

core/java/android/app/ActivityManager.java

@@ -2370,6 +2370,8 @@ public class ActivityManager {
         public int displayId;
         public int userId;
         public boolean visible;
+        // Index of the stack in the display's stack list, can be used for comparison of stack order
+        public int position;
 
         @Override
         public int describeContents() {
@@ -2397,6 +2399,7 @@ public class ActivityManager {
             dest.writeInt(displayId);
             dest.writeInt(userId);
             dest.writeInt(visible ? 1 : 0);
+            dest.writeInt(position);
             if (topActivity != null) {
                 dest.writeInt(1);
                 topActivity.writeToParcel(dest, 0);
@@ -2426,6 +2429,7 @@ public class ActivityManager {
             displayId = source.readInt();
             userId = source.readInt();
             visible = source.readInt() > 0;
+            position = source.readInt();
             if (source.readInt() > 0) {
                 topActivity = ComponentName.readFromParcel(source);
             }

packages/SystemUI/src/com/android/systemui/recents/misc/SystemServicesProxy.java

@@ -371,11 +371,19 @@ public class SystemServicesProxy {
         try {
             ActivityManager.StackInfo stackInfo = mIam.getStackInfo(
                     ActivityManager.StackId.HOME_STACK_ID);
+            ActivityManager.StackInfo fullscreenStackInfo = mIam.getStackInfo(
+                    ActivityManager.StackId.FULLSCREEN_WORKSPACE_STACK_ID);
             ComponentName topActivity = stackInfo.topActivity;
-            if (isHomeStackVisible != null) {
-                isHomeStackVisible.value = stackInfo.visible;
+            boolean homeStackVisibleNotOccluded = stackInfo.visible;
+            if (fullscreenStackInfo != null) {
+                boolean isFullscreenStackOccludingHome = fullscreenStackInfo.visible &&
+                        fullscreenStackInfo.position > stackInfo.position;
+                homeStackVisibleNotOccluded &= !isFullscreenStackOccludingHome;
             }
-            return (stackInfo.visible && topActivity != null
+            if (isHomeStackVisible != null) {
+                isHomeStackVisible.value = homeStackVisibleNotOccluded;
+            }
+            return (homeStackVisibleNotOccluded && topActivity != null
                     && topActivity.getPackageName().equals(RecentsImpl.RECENTS_PACKAGE)
                     && (topActivity.getClassName().equals(RecentsImpl.RECENTS_ACTIVITY)
                         || topActivity.getClassName().equals(RecentsTvImpl.RECENTS_TV_ACTIVITY)));

services/core/java/com/android/server/am/ActivityStackSupervisor.java

@@ -123,7 +123,6 @@ import static android.app.ActivityManager.StackId.PINNED_STACK_ID;
 import static android.content.Intent.FLAG_ACTIVITY_MULTIPLE_TASK;
 import static android.content.Intent.FLAG_ACTIVITY_NEW_TASK;
 import static android.content.pm.ActivityInfo.FLAG_SHOW_FOR_ALL_USERS;
-import static android.content.pm.ActivityInfo.RESIZE_MODE_FORCE_RESIZEABLE;
 import static android.content.pm.PackageManager.PERMISSION_GRANTED;
 import static android.os.Trace.TRACE_TAG_ACTIVITY_MANAGER;
 import static com.android.server.am.ActivityManagerDebugConfig.DEBUG_ALL;
@@ -3406,12 +3405,16 @@ public final class ActivityStackSupervisor implements DisplayListener {
     }
 
     private StackInfo getStackInfoLocked(ActivityStack stack) {
+        final ActivityDisplay display = mActivityDisplays.get(Display.DEFAULT_DISPLAY);
         StackInfo info = new StackInfo();
         mWindowManager.getStackBounds(stack.mStackId, info.bounds);
         info.displayId = Display.DEFAULT_DISPLAY;
         info.stackId = stack.mStackId;
         info.userId = stack.mCurrentUser;
         info.visible = stack.getStackVisibilityLocked(null) == STACK_VISIBLE;
+        info.position = display != null
+                ? display.mStacks.indexOf(stack)
+                : 0;
 
         ArrayList<TaskRecord> tasks = stack.getAllTasks();
         final int numTasks = tasks.size();