Fixed issue with moveTaskToBack on single stack devices

Icdad980eec64e081d15679600da07cf4431e40d6 allowed us to
properly return to the home acitvity when a task is moved
to back. However, this improperly moved the home task to
the front if it is the task we are moving to the back on
a single stack device. We now prevent the movement of the
home task to the front from happening.

Bug: 23088310
Change-Id: Ic21779cdb2d2007671d212d41fab5e68be2ae632

1 files changed, 7 insertions, 3 deletions

diff --git a/services/core/java/com/android/server/am/ActivityStack.java b/services/core/java/com/android/server/am/ActivityStack.java
index a75cc48..6e34876 100644
--- a/services/core/java/com/android/server/am/ActivityStack.java
+++ b/services/core/java/com/android/server/am/ActivityStack.java
@@ -3740,7 +3740,12 @@ final class ActivityStack {
         if (DEBUG_TRANSITION) Slog.v(TAG_TRANSITION, "Prepare to back transition: task=" + taskId);
 
         boolean prevIsHome = false;
-        if (tr.isOverHomeStack()) {
+
+        // If true, we should resume the home activity next if the task we are moving to the
+        // back is over the home stack. We force to false if the task we are moving to back
+        // is the home task and we don't want it resumed after moving to the back.
+        final boolean canGoHome = !tr.isHomeTask() && tr.isOverHomeStack();
+        if (canGoHome) {
             final TaskRecord nextTask = getNextTask(tr);
             if (nextTask != null) {
                 nextTask.setTaskToReturnTo(tr.getTaskToReturnTo());
@@ -3774,8 +3779,7 @@ final class ActivityStack {
         }
 
         final TaskRecord task = mResumedActivity != null ? mResumedActivity.task : null;
-        if (prevIsHome || task == tr && tr.isOverHomeStack()
-                || numTasks <= 1 && isOnHomeDisplay()) {
+        if (prevIsHome || (task == tr && canGoHome) || (numTasks <= 1 && isOnHomeDisplay())) {
             if (!mService.mBooting && !mService.mBooted) {
                 // Not ready yet!
                 return false;