[tracing] Make tab-view rerender after reset/clear

tracing/tracing/ui/base/tab_view_test.html

Index: tracing/tracing/ui/base/tab_view_test.html
diff --git a/tracing/tracing/ui/base/tab_view_test.html b/tracing/tracing/ui/base/tab_view_test.html
index fd880fd3b39644b35402599e54a12bd0fa546ae4..3e5f29fc8e5deaab7cf00f1364092f257baec3c4 100644
--- a/tracing/tracing/ui/base/tab_view_test.html
+++ b/tracing/tracing/ui/base/tab_view_test.html
@@ -122,5 +122,17 @@ tr.b.unittest.testSuite(function() {
     assert.strictEqual(tabView.selectedSubView, view2);
     assert.strictEqual(selectedTabChangeEventCount, 2);
   });
+
+  test('instantiate_twoTabsSwitch', function() {

[charliea (OOO until 10-5), 2017/01/25 21:47:42]

Does this test case actually reproduce the problem? I patched the CL locally and
the patched version and master seem to produce results that are identical
pixel-for-pixel

+    var tabView = document.createElement('tr-ui-b-tab-view');
+    tabView.label = '3 items selected.';
+    tabView.addSubView(createPowerSampleSubView());
+    tabView.addSubView(createAlertSubView());
+    this.addHTMLOutput(tabView);
+    tr.b.requestAnimationFrame(function() {
+      tabView.selectedSubView = tabView.tabs[1];
+    });
+  });
+
 });
 </script>