Add a helper function and update test results with ax role of table header.

content/browser/accessibility/dump_accessibility_tree_browsertest.cc

Index: content/browser/accessibility/dump_accessibility_tree_browsertest.cc
diff --git a/content/browser/accessibility/dump_accessibility_tree_browsertest.cc b/content/browser/accessibility/dump_accessibility_tree_browsertest.cc
index e386a212f098afa3d3327f7df41e7871c2df97a2..90ce25bedcd53a4c6db9358fa78d232f9271cc82 100644
--- a/content/browser/accessibility/dump_accessibility_tree_browsertest.cc
+++ b/content/browser/accessibility/dump_accessibility_tree_browsertest.cc
@@ -961,18 +961,17 @@ IN_PROC_BROWSER_TEST_F(DumpAccessibilityTreeTest, AccessibilityTab) {
   RunHtmlTest(FILE_PATH_LITERAL("tab.html"));
 }
 
-IN_PROC_BROWSER_TEST_F(DumpAccessibilityTreeTest,
-                       DISABLED_AccessibilityTableSimple) {
+IN_PROC_BROWSER_TEST_F(DumpAccessibilityTreeTest, AccessibilityTableSimple) {
   RunHtmlTest(FILE_PATH_LITERAL("table-simple.html"));
 }
 
 IN_PROC_BROWSER_TEST_F(DumpAccessibilityTreeTest,
-                       DISABLED_AccessibilityTableThRowHeader) {
+                       AccessibilityTableThRowHeader) {
   RunHtmlTest(FILE_PATH_LITERAL("table-th-rowheader.html"));
 }
 
 IN_PROC_BROWSER_TEST_F(DumpAccessibilityTreeTest,
-                       DISABLED_AccessibilityTableTbodyTfoot) {
+                       AccessibilityTableTbodyTfoot) {
   RunHtmlTest(FILE_PATH_LITERAL("table-thead-tbody-tfoot.html"));
 }