From 4ad9856eb815c03723f9fe5f78518077b9c713c7 Mon Sep 17 00:00:00 2001
From: Jorim Jaggi <jjaggi@google.com>
Date: Tue, 19 Apr 2016 20:30:47 -0700
Subject: [PATCH] Disallow changing stacks if top activity

When we attach an activity to an existing
task, and that task is already on top,
disallow changing stacks altogether even
if launch stack id is set.

Bug: 28026847
Change-Id: Ie70f0585a29dc1b85a5093624fede32110be3c76
---
 .../com/android/server/am/ActivityStarter.java  | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/services/core/java/com/android/server/am/ActivityStarter.java b/services/core/java/com/android/server/am/ActivityStarter.java
index 9c93f2c54adb2..3ffdb9553ee08 100644
--- a/services/core/java/com/android/server/am/ActivityStarter.java
+++ b/services/core/java/com/android/server/am/ActivityStarter.java
@@ -582,7 +582,7 @@ class ActivityStarter {
                 null /*voiceInteractor*/, null /*resultTo*/, null /*resultWho*/,
                 0 /*requestCode*/, 0 /*callingPid*/, 0 /*callingUid*/, null /*callingPackage*/,
                 0 /*realCallingPid*/, 0 /*realCallingUid*/, 0 /*startFlags*/, null /*options*/,
-                false /*ignoreTargetSecurity*/, false /*componentSpecified*/,  null /*outActivity*/,
+                false /*ignoreTargetSecurity*/, false /*componentSpecified*/, null /*outActivity*/,
                 null /*container*/, null /*inTask*/);
         if (mSupervisor.inResumeTopActivity) {
             // If we are in resume section already, home activity will be initialized, but not
@@ -1432,7 +1432,7 @@ class ActivityStarter {
                             == (FLAG_ACTIVITY_NEW_TASK | FLAG_ACTIVITY_CLEAR_TASK);
                 if (!willClearTask) {
                     final ActivityStack launchStack = getLaunchStack(
-                            mStartActivity, mLaunchFlags, mStartActivity.task, mOptions, true);
+                            mStartActivity, mLaunchFlags, mStartActivity.task, mOptions);
                     if (launchStack == null || launchStack == mTargetStack) {
                         // We only want to move to the front, if we aren't going to launch on a
                         // different stack. If we launch on a different stack, we will put the
@@ -1606,8 +1606,11 @@ class ActivityStarter {
         // We only want to allow changing stack if the target task is not the top one,
         // otherwise we would move the launching task to the other side, rather than show
         // two side by side.
-        final boolean launchToSideAllowed = sourceTask.stack.topTask() != sourceTask;
-        mTargetStack = getLaunchStack(mStartActivity, mLaunchFlags, mStartActivity.task, mOptions, launchToSideAllowed);
+        final boolean moveStackAllowed = sourceTask.stack.topTask() != sourceTask;
+        if (moveStackAllowed) {
+            mTargetStack = getLaunchStack(mStartActivity, mLaunchFlags, mStartActivity.task,
+                    mOptions);
+        }
 
         if (mTargetStack == null) {
             mTargetStack = sourceTask.stack;
@@ -1780,7 +1783,7 @@ class ActivityStarter {
             return mSupervisor.mHomeStack;
         }
 
-        ActivityStack stack = getLaunchStack(r, launchFlags, task, aOptions, true);
+        ActivityStack stack = getLaunchStack(r, launchFlags, task, aOptions);
         if (stack != null) {
             return stack;
         }
@@ -1845,7 +1848,7 @@ class ActivityStarter {
     }
 
     private ActivityStack getLaunchStack(ActivityRecord r, int launchFlags, TaskRecord task,
-            ActivityOptions aOptions, boolean launchToSideAllowed) {
+            ActivityOptions aOptions) {
         final int launchStackId =
                 (aOptions != null) ? aOptions.getLaunchStackId() : INVALID_STACK_ID;
 
@@ -1857,7 +1860,7 @@ class ActivityStarter {
             return mSupervisor.getStack(FULLSCREEN_WORKSPACE_STACK_ID, CREATE_IF_NEEDED, ON_TOP);
         }
 
-        if (!launchToSideAllowed || (launchFlags & FLAG_ACTIVITY_LAUNCH_ADJACENT) == 0) {
+        if ((launchFlags & FLAG_ACTIVITY_LAUNCH_ADJACENT) == 0) {
             return null;
         }
         // Otherwise handle adjacent launch.