Add API to request light navigation bar in theme

Such that splash screens can already have a light navigation bar,
avoiding a janky flash.

This is the CL on master for this change, which only cleans up the
API.

Test: CtsSystemUiTestCases
Bug: 66986286
Bug: 63630024
Change-Id: I81b34fefeb336ac2269dc5e6b98cc0b6045cea70
diff --git a/api/current.txt b/api/current.txt
index c677089..2f22ba4 100644
--- a/api/current.txt
+++ b/api/current.txt
@@ -919,6 +919,7 @@
     field public static final int multiprocess = 16842771; // 0x1010013
     field public static final int name = 16842755; // 0x1010003
     field public static final int navigationBarColor = 16843858; // 0x1010452
+    field public static final int navigationBarDividerColor = 16844141; // 0x101056d
     field public static final int navigationContentDescription = 16843969; // 0x10104c1
     field public static final int navigationIcon = 16843968; // 0x10104c0
     field public static final int navigationMode = 16843471; // 0x10102cf
diff --git a/api/system-current.txt b/api/system-current.txt
index bfd1661..7841bdf 100644
--- a/api/system-current.txt
+++ b/api/system-current.txt
@@ -1051,6 +1051,7 @@
     field public static final int multiprocess = 16842771; // 0x1010013
     field public static final int name = 16842755; // 0x1010003
     field public static final int navigationBarColor = 16843858; // 0x1010452
+    field public static final int navigationBarDividerColor = 16844141; // 0x101056d
     field public static final int navigationContentDescription = 16843969; // 0x10104c1
     field public static final int navigationIcon = 16843968; // 0x10104c0
     field public static final int navigationMode = 16843471; // 0x10102cf
diff --git a/api/test-current.txt b/api/test-current.txt
index 2512e8e..89e0d5b 100644
--- a/api/test-current.txt
+++ b/api/test-current.txt
@@ -919,6 +919,7 @@
     field public static final int multiprocess = 16842771; // 0x1010013
     field public static final int name = 16842755; // 0x1010003
     field public static final int navigationBarColor = 16843858; // 0x1010452
+    field public static final int navigationBarDividerColor = 16844141; // 0x101056d
     field public static final int navigationContentDescription = 16843969; // 0x10104c1
     field public static final int navigationIcon = 16843968; // 0x10104c0
     field public static final int navigationMode = 16843471; // 0x10102cf
diff --git a/core/res/res/values/attrs.xml b/core/res/res/values/attrs.xml
index 61b4123..11cdb76 100644
--- a/core/res/res/values/attrs.xml
+++ b/core/res/res/values/attrs.xml
@@ -2056,11 +2056,11 @@
              Corresponds to {@link android.view.Window#setNavigationBarColor(int)}. -->
         <attr name="navigationBarColor" format="color" />
 
-        <!-- @hide
-             Shows 1dp line of the specified color between the navigation bar and the app content.
+        <!-- Shows a thin line of the specified color between the navigation bar and the app
+             content.
              <p>For this to take effect, the window must be drawing the system bar backgrounds with
              {@link android.R.attr#windowDrawsSystemBarBackgrounds} and the navigation bar must not
-               have been requested to be translucent with
+             have been requested to be translucent with
              {@link android.R.attr#windowTranslucentNavigation}. -->
         <attr name="navigationBarDividerColor" format="color" />
 
diff --git a/core/res/res/values/public.xml b/core/res/res/values/public.xml
index 9b2f185..e9d574a 100644
--- a/core/res/res/values/public.xml
+++ b/core/res/res/values/public.xml
@@ -2846,6 +2846,8 @@
         <public name="showWhenLocked"/>
         <public name="turnScreenOn"/>
         <public name="classLoader" />
+        <public name="windowLightNavigationBar" />
+        <public name="navigationBarDividerColor" />
     </public-group>
 
     <public-group type="style" first-id="0x010302e0">
@@ -2875,10 +2877,6 @@
          =============================================================== -->
     <eat-comment />
 
-    <public-group type="attr" first-id="0x0101056c">
-      <public name="windowLightNavigationBar" />
-    </public-group>
-
   <!-- ===============================================================
        DO NOT ADD UN-GROUPED ITEMS HERE