Rename RenderCanvas to PaintingCanvas to avoid confusion with other classes that inherit from Rende…

sky/sdk/lib/widgets/tabs.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 'dart:math' as math;
 
 import 'package:sky/rendering/box.dart';
 import 'package:sky/rendering/object.dart';
 import 'package:sky/widgets/basic.dart';
 import 'package:sky/widgets/icon.dart';
@@ skipping 113 matching lines @@
       child.parentData.position = new Point(x, 0.0);
       x += tabWidth;
       child = child.parentData.nextSibling;
     }
   }
 
   void hitTestChildren(HitTestResult result, { Point position }) {
     defaultHitTestChildren(result, position: position);
   }
 
-  void _paintIndicator(RenderCanvas canvas, RenderBox selectedTab, Offset offset) {
+  void _paintIndicator(PaintingCanvas canvas, RenderBox selectedTab, Offset offset) {
     if (indicatorColor == null)
       return;
 
     var size = new Size(selectedTab.size.width, _kTabIndicatorHeight);
     var point = new Point(
       selectedTab.parentData.position.x,
       _tabBarHeight - _kTabIndicatorHeight
     );
     Rect rect = (point + offset) & size;
     canvas.drawRect(rect, new Paint()..color = indicatorColor);
   }
 
-  void paint(RenderCanvas canvas, Offset offset) {
+  void paint(PaintingCanvas canvas, Offset offset) {
     if (backgroundColor != null) {
       Rect rect = offset & size;
       canvas.drawRect(rect, new Paint()..color = backgroundColor);
     }
 
     int index = 0;
     RenderBox child = firstChild;
     while (child != null) {
       assert(child.parentData is TabBarParentData);
       canvas.paintChild(child, child.parentData.position + offset);
@@ skipping 184 matching lines @@
       onChanged: _handleSelectedIndexChanged,
       selectedIndex: selectedIndex
     );
 
     Widget content = views[selectedIndex].buildContent();
     return new Flex([tabBar, new Flexible(child: content)],
       direction: FlexDirection.vertical
     );
   }
 }