Fix recents crashing during docked stack resize.

Whether acitvity window should be preserved during the relaunch is
controlled by the activity manager and the existence of
non-client-decor should not affect it. For example, docked activities
will not have non-client-decor, but we would like to preserve them
anyway.

Bug: 24573657
Change-Id: I5d4852c3b7c26ac3ec1bbc105639f75b67d1d3ad

core/java/android/app/ActivityThread.java

@@ -3956,13 +3956,12 @@ public final class ActivityThread {
                 }
                 IBinder wtoken = v.getWindowToken();
                 if (r.activity.mWindowAdded) {
-                    boolean reuseForResize = r.window.hasNonClientDecorView() && r.mPreserveWindow;
-                    if (r.onlyLocalRequest || reuseForResize) {
+                    if (r.onlyLocalRequest || r.mPreserveWindow) {
                         // Hold off on removing this until the new activity's
                         // window is being added.
                         r.mPendingRemoveWindow = r.window;
                         r.mPendingRemoveWindowManager = wm;
-                        if (reuseForResize) {
+                        if (r.mPreserveWindow) {
                             // We can only keep the part of the view hierarchy that we control,
                             // everything else must be removed, because it might not be able to
                             // behave properly when activity is relaunching.

core/java/android/view/Window.java

@@ -28,9 +28,8 @@ import android.content.Context;
 import android.content.res.Configuration;
 import android.content.res.Resources;
 import android.content.res.TypedArray;
-import android.graphics.drawable.Drawable;
 import android.graphics.PixelFormat;
-import android.graphics.Rect;
+import android.graphics.drawable.Drawable;
 import android.media.session.MediaController;
 import android.net.Uri;
 import android.os.Bundle;
@@ -2007,16 +2006,6 @@ public abstract class Window {
      */
     public abstract void setNavigationBarColor(@ColorInt int color);
 
-    /**
-     * Get information whether the activity has non client decoration view. These views are used in
-     * the multi window environment, to provide dragging handle and maximize/close buttons.
-     *
-     * @hide
-     */
-    public boolean hasNonClientDecorView() {
-        return false;
-    }
-
     /** @hide */
     public void setTheme(int resId) {
     }

core/java/com/android/internal/policy/PhoneWindow.java

@@ -488,7 +488,7 @@ public class PhoneWindow extends Window implements MenuBuilder.Callback {
     }
 
     public void clearContentView() {
-        if (mNonClientDecorView.getChildCount() > 1) {
+        if (mNonClientDecorView != null && mNonClientDecorView.getChildCount() > 1) {
             mNonClientDecorView.removeViewAt(1);
         }
     }
@@ -5413,15 +5413,9 @@ public class PhoneWindow extends Window implements MenuBuilder.Callback {
      * @Return Returns true if the window should show a shadow.
      **/
     private boolean nonClientDecorHasShadow(int workspaceId) {
-        // TODO(skuhne): Add side by side mode here to add a decor.
         return workspaceId == FREEFORM_WORKSPACE_STACK_ID;
     }
 
-    @Override
-    public boolean hasNonClientDecorView() {
-        return mNonClientDecorView != null;
-    }
-
     @Override
     public void setTheme(int resid) {
         mTheme = resid;