Article not exposed with correct IA2 Role

Article tag and aria role article are not exposed with correct IA2 Role.
Correct IA2 role for article is ROLE_SYSTEM_DOCUMENT.

BUG=281890

Review URL: https://codereview.chromium.org/602353003

Cr-Commit-Position: refs/heads/master@{#296908}

content/browser/accessibility/browser_accessibility_win.cc

@@ -3391,8 +3391,7 @@ void BrowserAccessibilityWin::InitRoleAndState() {
       ia_role_ = ROLE_SYSTEM_APPLICATION;
       break;
     case ui::AX_ROLE_ARTICLE:
-      ia_role_ = ROLE_SYSTEM_GROUPING;
-      ia2_role_ = IA2_ROLE_SECTION;
+      ia_role_ = ROLE_SYSTEM_DOCUMENT;
       ia_state_ |= STATE_SYSTEM_READONLY;
       break;
     case ui::AX_ROLE_BUSY_INDICATOR:

content/test/data/accessibility/article-expected-win.txt

 ROLE_SYSTEM_DOCUMENT READONLY FOCUSABLE
-    IA2_ROLE_SECTION READONLY xml-roles:article
+    ROLE_SYSTEM_DOCUMENT READONLY xml-roles:article
         ROLE_SYSTEM_STATICTEXT name='This is an article element.'
-    IA2_ROLE_SECTION READONLY xml-roles:article
+    ROLE_SYSTEM_DOCUMENT READONLY xml-roles:article
         ROLE_SYSTEM_STATICTEXT name='This is an ARIA article.'