Add Select-to-Speak to accessibilityFeatures API

Bug: None
Change-Id: I6dd41369875d445a90598e01c4c31f59094e267e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1592681Reviewed-by: David Tseng <dtseng@chromium.org>
Reviewed-by: Toni Baržić <tbarzic@chromium.org>
Commit-Queue: Anastasia Helfinstein <anastasi@google.com>
Cr-Commit-Position: refs/heads/master@{#656436}

chrome/browser/extensions/api/preference/preference_api.cc

@@ -159,6 +159,9 @@ const PrefMappingEntry kPrefMapping[] = {
     {"screenMagnifier", ash::prefs::kAccessibilityScreenMagnifierEnabled,
      APIPermission::kAccessibilityFeaturesRead,
      APIPermission::kAccessibilityFeaturesModify},
+    {"selectToSpeak", ash::prefs::kAccessibilitySelectToSpeakEnabled,
+     APIPermission::kAccessibilityFeaturesRead,
+     APIPermission::kAccessibilityFeaturesModify},
     {"spokenFeedback", ash::prefs::kAccessibilitySpokenFeedbackEnabled,
      APIPermission::kAccessibilityFeaturesRead,
      APIPermission::kAccessibilityFeaturesModify},