Update incognito toolbar button's accessible title.

Accessible name of incognito menu is updated to tell the number of open
incognito windows when incognito window counter is active.

Bug: 896235
Change-Id: I16deed985d9cf8170d6739f083f0c352df44c435
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1569932Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Reviewed-by: Peter Boström <pbos@chromium.org>
Commit-Queue: Ramin Halavati <rhalavati@chromium.org>
Cr-Commit-Position: refs/heads/master@{#652521}

chrome/browser/ui/views/profiles/avatar_toolbar_button.cc

@@ -133,8 +133,12 @@ void AvatarToolbarButton::UpdateText() {
   if (IsIncognito()) {
     int incognito_window_count =
         BrowserList::GetIncognitoSessionsActiveForProfile(profile_);
-    if (!IsIncognitoCounterActive())
+    if (IsIncognitoCounterActive()) {
+      SetAccessibleName(l10n_util::GetPluralStringFUTF16(
+          IDS_INCOGNITO_BUBBLE_ACCESSIBLE_TITLE, incognito_window_count));
+    } else {
       incognito_window_count = 1;
+    }
     text = l10n_util::GetPluralStringFUTF16(IDS_AVATAR_BUTTON_INCOGNITO,
                                             incognito_window_count);
   } else if (sync_state == SyncState::kError) {