Add quick controls

    Bug: http://b/issue?id=3277888
    Added Quick Controls Lab setting
    Implemented Quick Controls UI

Change-Id: I72011daf9140aa5d15c8b785126867c10bbc5501
diff --git a/res/xml/preference_headers.xml b/res/xml/preference_headers.xml
index 1a54990..8533a3a 100644
--- a/res/xml/preference_headers.xml
+++ b/res/xml/preference_headers.xml
@@ -35,4 +35,9 @@
     <header android:fragment="com.android.browser.preferences.AdvancedPreferencesFragment"
         android:title="@string/pref_extras_title"
     />
+
+    <header android:fragment="com.android.browser.preferences.LabPreferencesFragment"
+        android:title="@string/pref_lab_title"
+    />
+
 </preference-headers>