SizeObserver crusade: Remove SizeObserver

packages/flutter/lib/src/rendering/proxy_box.dart

@@ -5,7 +5,6 @@
 import 'package:flutter/gestures.dart';
 import 'package:vector_math/vector_math_64.dart';
 
-import 'basic_types.dart';
 import 'box.dart';
 import 'debug.dart';
 import 'object.dart';
@@ -1167,33 +1166,6 @@ class RenderFractionalTranslation extends RenderProxyBox {
   }
 }
 
-/// Calls [onSizeChanged] whenever the child's layout size changes
-///
-/// Because size observer calls its callback during layout, you cannot modify
-/// layout information during the callback.
-class RenderSizeObserver extends RenderProxyBox {
-  RenderSizeObserver({
-    this.onSizeChanged,
-    RenderBox child
-  }) : super(child) {
-    assert(onSizeChanged != null);
-  }
-
-  /// The callback to call whenever the child's layout size changes
-  ValueChanged<Size> onSizeChanged;
-
-  void performLayout() {
-    Size oldSize = hasSize ? size : null;
-    super.performLayout();
-    if (oldSize != size) {
-      // We make a copy of the Size object here because if we leak a _DebugSize
-      // object out of the render tree, we can get confused later if it comes
-      // back and gets set as the size property of a RenderBox.
-      onSizeChanged(new Size(size.width, size.height));
-    }
-  }
-}
-
 abstract class CustomPainter {
   const CustomPainter();
 

packages/flutter/lib/src/widgets/basic.dart

@@ -828,30 +828,6 @@ class Viewport extends OneChildRenderObjectWidget {
   }
 }
 
-/// Calls [onSizeChanged] whenever the child's layout size changes
-///
-/// Because size observer calls its callback during layout, you cannot modify
-/// layout information during the callback.
-class SizeObserver extends OneChildRenderObjectWidget {
-  SizeObserver({ Key key, this.onSizeChanged, Widget child })
-    : super(key: key, child: child) {
-    assert(onSizeChanged != null);
-  }
-
-  /// The callback to call whenever the child's layout size changes
-  final ValueChanged<Size> onSizeChanged;
-
-  RenderSizeObserver createRenderObject() => new RenderSizeObserver(onSizeChanged: onSizeChanged);
-
-  void updateRenderObject(RenderSizeObserver renderObject, SizeObserver oldWidget) {
-    renderObject.onSizeChanged = onSizeChanged;
-  }
-
-  void didUnmountRenderObject(RenderSizeObserver renderObject) {
-    renderObject.onSizeChanged = null;
-  }
-}
-
 
 // CONTAINER
 

packages/flutter/test/widget/block_test.dart

@@ -22,7 +22,6 @@ void main() {
           ]
         )
       );
-      tester.pump(); // for SizeObservers
 
       Point middleOfContainer = tester.getCenter(tester.findText('Hello'));
       Point target = tester.getCenter(tester.findElementByKey(blockKey));
@@ -100,7 +99,6 @@ void main() {
       }
 
       tester.pumpWidget(buildBlock(ViewportAnchor.end));
-      tester.pump(); // for SizeObservers
 
       Point target = const Point(200.0, 200.0);
       tester.tapAt(target);
@@ -108,7 +106,6 @@ void main() {
       expect(second, equals(1));
 
       tester.pumpWidget(buildBlock(ViewportAnchor.start));
-      tester.pump(); // for SizeObservers
 
       tester.tapAt(target);
       expect(first, equals(1));

packages/flutter/test/widget/size_observer_test.dart

-// Copyright 2015 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-import 'package:flutter_test/flutter_test.dart';
-import 'package:flutter/rendering.dart';
-import 'package:flutter/widgets.dart';
-import 'package:test/test.dart';
-
-void main() {
-  test('SizeObserver notices zero size', () {
-    testWidgets((WidgetTester tester) {
-      List<Size> results = <Size>[];
-      tester.pumpWidget(new Center(
-        child: new SizeObserver(
-          onSizeChanged: (Size size) { results.add(size); },
-          child: new Container(width:0.0, height:0.0)
-        )
-      ));
-      expect(results, equals([Size.zero]));
-      tester.pump();
-      expect(results, equals([Size.zero]));
-      tester.pumpWidget(new Center(
-        child: new SizeObserver(
-          onSizeChanged: (Size size) { results.add(size); },
-          child: new Container(width:100.0, height:0.0)
-        )
-      ));
-      expect(results, equals([Size.zero, const Size(100.0, 0.0)]));
-      tester.pump();
-      expect(results, equals([Size.zero, const Size(100.0, 0.0)]));
-      tester.pumpWidget(new Center(
-        child: new SizeObserver(
-          onSizeChanged: (Size size) { results.add(size); },
-          child: new Container(width:0.0, height:0.0)
-        )
-      ));
-      expect(results, equals([Size.zero, const Size(100.0, 0.0), Size.zero]));
-      tester.pump();
-      expect(results, equals([Size.zero, const Size(100.0, 0.0), Size.zero]));
-      tester.pumpWidget(new Center(
-        child: new SizeObserver(
-          onSizeChanged: (Size size) { results.add(size); },
-          child: new Container(width:0.0, height:0.0)
-        )
-      ));
-      expect(results, equals([Size.zero, const Size(100.0, 0.0), Size.zero]));
-    });
-  });
-}