Move desired task to top if not already there.

Under certain circumstances when launching a new activity, the
topmost stack activity is moved to the front even though the
activity is being created in a different task.

This checks if the topmost stack task matches the desired
task and if not, moves the desired task to the top.

Also make activity dump ordering consistent.

Fixes bug 17721767.

Change-Id: I59397f31b629a208f3863887c57d6f6fb1f6e1f3

1 files changed, 9 insertions, 4 deletions

diff --git a/services/core/java/com/android/server/am/ActivityStackSupervisor.java b/services/core/java/com/android/server/am/ActivityStackSupervisor.java
index bbfb62abff05..879ddc040519 100644
--- a/services/core/java/com/android/server/am/ActivityStackSupervisor.java
+++ b/services/core/java/com/android/server/am/ActivityStackSupervisor.java
@@ -2058,7 +2058,13 @@ public final class ActivityStackSupervisor implements DisplayListener {
             }
             targetStack = sourceTask.stack;
             targetStack.moveToFront();
-            mWindowManager.moveTaskToTop(targetStack.topTask().taskId);
+            final TaskRecord topTask = targetStack.topTask();
+            if (topTask != sourceTask) {
+                targetStack.moveTaskToFrontLocked(sourceTask, r, options);
+                Slog.w(TAG, "top task and source task don't match. would have caused anr");
+            } else {
+                mWindowManager.moveTaskToTop(topTask.taskId);
+            }
             if (!addingToTask && (launchFlags&Intent.FLAG_ACTIVITY_CLEAR_TOP) != 0) {
                 // In this case, we are adding the activity to an existing
                 // task, but the caller has asked to clear that task if the
@@ -3097,10 +3103,9 @@ public final class ActivityStackSupervisor implements DisplayListener {
         for (int displayNdx = 0; displayNdx < mActivityDisplays.size(); ++displayNdx) {
             ActivityDisplay activityDisplay = mActivityDisplays.valueAt(displayNdx);
             pw.print("Display #"); pw.print(activityDisplay.mDisplayId);
-                    pw.println(" (activities from bottom to top):");
+                    pw.println(" (activities from top to bottom):");
             ArrayList<ActivityStack> stacks = activityDisplay.mStacks;
-            final int numStacks = stacks.size();
-            for (int stackNdx = 0; stackNdx < numStacks; ++stackNdx) {
+            for (int stackNdx = stacks.size() - 1; stackNdx >= 0; --stackNdx) {
                 final ActivityStack stack = stacks.get(stackNdx);
                 StringBuilder stackHeader = new StringBuilder(128);
                 stackHeader.append("  Stack #");