Add Full Immersive Mode support for API 19+

Added immersive mode to the browser. Previous
implementation was from 2011 and would only
hide the status bar. Now we hide the entire
System UI where supported (api 19+).

Change-Id: I5b3c6079c38bd2035c3bf9ce60887ff85ccfa2a2
diff --git a/res/values/strings.xml b/res/values/strings.xml
index 89df52d..8090344 100644
--- a/res/values/strings.xml
+++ b/res/values/strings.xml
@@ -646,10 +646,10 @@
       Use Google Instant when you use Google Search, to show results as you
       type (this can increase data use).</string>
     <!-- Title for the fullscreen lab feature [CHAR LIMIT=40] -->
-    <string name="pref_lab_fullscreen">Fullscreen</string>
+    <string name="pref_lab_fullscreen">Immersive</string>
     <!-- Summary for the fullscreen lab feature [CHAR LIMIT=120] -->
     <string name="pref_lab_fullscreen_summary">
-      Use fullscreen mode to hide the status bar</string>
+      Make the browser fullscreen</string>
     <!-- Title for bandwidth management preference [CHAR LIMIT=25] -->
     <string name="pref_data_title">Bandwidth management</string>
     <!-- Title for search preloading [CHAR LIMIT=40] -->