Fix theme changing: turns out we were not reparenting stateful surviving nodes...

Fix theme changing: turns out we were not reparenting stateful surviving nodes when their parents changed identity

This also makes the optimistic/pessimistic mode switch change the active theme, because why not.

While I was at it I also provided a debug boolean argument to runApp() to make it possible to profile more easily.

R=abarth@chromium.org

Review URL: https://codereview.chromium.org/1215023002.

sdk/example/stocks/lib/main.dart

@@ -61,22 +61,35 @@ class StocksApp extends App {
     });
   }
 
-  Widget build() {
-    return new Theme(
-      data: new ThemeData.light(
+   Widget build() {
+
+    ThemeData theme;
+    if (stockMode == StockMode.optimistic) {
+      theme = new ThemeData.light(
         primary: colors.Purple,
         accent: colors.RedAccent,
-        darkToolbar: true),
-      child: new Navigator(_navigationState)
-    );
-  }
+        darkToolbar: true
+      );
+    } else {
+      theme = new ThemeData.dark(
+        primary: colors.Red,
+        accent: colors.PurpleAccent
+      );
+    }
+
+    return new Theme(
+      data: theme,
+       child: new Navigator(_navigationState)
+     );
+   }
 }
 
 void main() {
   print("starting stocks app!");
-  runApp(new StocksApp());
+  runApp(new StocksApp(), enableProfilingLoop: true);
+  // set enableProfilingLoop to true to make the app rebuild continually every 20ms
   SkyBinding.instance.onFrame = () {
-    // uncomment this for debugging:
+    // uncomment this to print the RenderObject tree every frame:
     // SkyBinding.instance.debugDumpRenderTree();
   };
 }

sdk/lib/painting/box_painter.dart

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:math' as math;
 import 'dart:sky' as sky;
 import 'dart:sky' show Point, Offset, Size, Rect, Color, Paint, Path;
 

sdk/lib/widgets/widget.dart

@@ -50,6 +50,8 @@ abstract class Widget {
 
   void setParent(Widget newParent) {
     assert(!_notifyingMountStatus);
+    if (_parent == newParent)
+      return;
     _parent = newParent;
     if (newParent == null) {
       if (_mounted) {
@@ -146,6 +148,7 @@ abstract class Widget {
         if (node._retainStatefulNodeIfPossible(oldNode)) {
           assert(oldNode.mounted);
           assert(!node.mounted);
+          oldNode.setParent(this);
           oldNode._sync(node, slot);
           assert(oldNode.root is RenderObject);
           return oldNode;
@@ -957,9 +960,14 @@ class AppContainer extends AbstractWidgetRoot {
   Widget build() => new RenderViewWrapper(child: app);
 }
 
-void runApp(App app, { RenderView renderViewOverride }) {
+void runApp(App app, { RenderView renderViewOverride, bool enableProfilingLoop: false }) {
   WidgetSkyBinding.initWidgetSkyBinding(renderViewOverride: renderViewOverride);
   new AppContainer(app);
+  if (enableProfilingLoop) {
+    new Timer.periodic(const Duration(milliseconds: 20), (_) {
+      app.scheduleBuild();
+    });
+  }
 }
 
 typedef Widget Builder();