Merge pull request #729 from Hixie/rendering

Reorder bootstrapping code in rendering/ for slightly cleaner code.

Author: abarth

sky/packages/sky/lib/rendering/object.dart

@@ -394,14 +394,14 @@ abstract class RenderObject extends AbstractNode implements HitTestTarget {
   void scheduleInitialLayout() {
     assert(attached);
     assert(parent is! RenderObject);
+    assert(!_debugDoingLayout);
     assert(_relayoutSubtreeRoot == null);
     _relayoutSubtreeRoot = this;
     assert(() {
       _debugCanParentUseSize = false;
       return true;
     });
     _nodesNeedingLayout.add(this);
-    scheduler.ensureVisualUpdate();
   }
   static void flushLayout() {
     sky.tracing.begin('RenderObject.flushLayout');
@@ -648,6 +648,7 @@ abstract class RenderObject extends AbstractNode implements HitTestTarget {
     assert(parent is! RenderObject);
     assert(!_debugDoingPaint);
     assert(hasLayer);
+    assert(_layer == null);
     _layer = rootLayer;
     assert(_needsPaint);
     _nodesNeedingPaint.add(this);

sky/packages/sky/lib/rendering/sky_binding.dart

@@ -40,11 +40,10 @@ class SkyBinding {
     sky.view.setMetricsChangedCallback(_handleMetricsChanged);
     scheduler.init();
     if (renderViewOverride == null) {
-      _renderView = new RenderView(child: root);
+      _renderView = new RenderView(child: root, devicePixelRatio: sky.view.devicePixelRatio);
       _renderView.attach();
       _renderView.rootConstraints = _createConstraints();
-      _renderView.scheduleInitialLayout();
-      _renderView.initializeLayerTree();
+      _renderView.scheduleInitialFrame();
     } else {
       _renderView = renderViewOverride;
     }

sky/packages/sky/lib/rendering/view.dart

@@ -4,6 +4,7 @@
 
 import 'dart:sky' as sky;
 
+import 'package:sky/base/scheduler.dart' as scheduler;
 import 'package:sky/rendering/layer.dart';
 import 'package:sky/rendering/object.dart';
 import 'package:sky/rendering/box.dart';
@@ -21,17 +22,20 @@ class ViewConstraints {
 class RenderView extends RenderObject with RenderObjectWithChildMixin<RenderBox> {
   RenderView({
     RenderBox child,
+    this.devicePixelRatio,
     this.timeForRotation: const Duration(microseconds: 83333)
   }) {
     this.child = child;
   }
 
+  final double devicePixelRatio;
+  Duration timeForRotation;
+
   Size _size = Size.zero;
   Size get size => _size;
 
   int _orientation; // 0..3
   int get orientation => _orientation;
-  Duration timeForRotation;
 
   ViewConstraints _rootConstraints;
   ViewConstraints get rootConstraints => _rootConstraints;
@@ -42,10 +46,11 @@ class RenderView extends RenderObject with RenderObjectWithChildMixin<RenderBox>
     markNeedsLayout();
   }
 
-  void initializeLayerTree() {
-    final double devicePixelRatio = sky.view.devicePixelRatio;
+  void scheduleInitialFrame() {
     Matrix4 logicalToDeviceZoom = new Matrix4.diagonal3Values(devicePixelRatio, devicePixelRatio, 1.0);
+    scheduleInitialLayout();
     scheduleInitialPaint(new TransformLayer(transform: logicalToDeviceZoom));
+    scheduler.ensureVisualUpdate();
   }
 
   // We never call layout() on this class, so this should never get