[omnibox] Add accessibility label to suggestions with tab switch button

For suggestions with a tab switch button, advertise the ability to tab
over to it and press enter, in the accessibility label.

Bug: 780835, 853911, 853929
Change-Id: I91649d0517ab6e75970e49b5358e7d210c914071
Reviewed-on: https://chromium-review.googlesource.com/1106706Reviewed-by: Aaron Leventhal <aleventhal@chromium.org>
Reviewed-by: Justin Donnelly <jdonnelly@chromium.org>
Commit-Queue: Kevin Bailey <krb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#575283}

components/omnibox/browser/autocomplete_match_type.cc

@@ -106,8 +106,12 @@ base::string16 AutocompleteMatchType::ToAccessibilityLabel(
     *label_prefix_length = 0;
 
   int message = message_ids[match.type];
-  if (!message)
-    return match_text;
+  if (!message) {
+    if (!match.has_tab_match)
+      return match_text;
+    else
+      return l10n_util::GetStringFUTF16(IDS_ACC_TAB_SWITCH_SUFFIX, match_text);
+  }
 
   const base::string16 sentinal =
       base::WideToUTF16(kAccessibilityLabelPrefixEndSentinal);
@@ -159,9 +163,14 @@ base::string16 AutocompleteMatchType::ToAccessibilityLabel(
                   l10n_util::GetStringFUTF16(message, sentinal));
   }
 
-  return has_description
-             ? l10n_util::GetStringFUTF16(message, match_text, description)
-             : l10n_util::GetStringFUTF16(message, match_text);
+  const base::string16 base_message =
+      has_description
+          ? l10n_util::GetStringFUTF16(message, match_text, description)
+          : l10n_util::GetStringFUTF16(message, match_text);
+  if (!match.has_tab_match)
+    return base_message;
+  else
+    return l10n_util::GetStringFUTF16(IDS_ACC_TAB_SWITCH_SUFFIX, base_message);
 }
 
 // static

components/omnibox_strings.grdp

@@ -87,4 +87,8 @@
   <message name="IDS_ACC_AUTOCOMPLETE_N_OF_M" desc="Text for screenreaders describing the current matche's position in the list of suggestions.">
     <ph name="FRIENDLY_MATCH_TEXT">$1<ex>The Chromium Projects http://www.chromium.org bookmark</ex></ph>, <ph name="MATCH_POSITION">$2<ex>2</ex></ph> of <ph name="NUM_MATCHES">$3<ex>3</ex></ph>
   </message>
+  <!-- Accessibility suffix for suggestions with a tab switch match. Comma is important. -->
+  <message name="IDS_ACC_TAB_SWITCH_SUFFIX" desc="Suffix for tab switch suggestions to explain keystroke used to switch.">
+    <ph name="TAB_SWITCH_SUFFIX">$1, currently open, press tab then enter to switch to the open tab</ph>
+  </message>
 </grit-part>