Remove hardcode color of sliding tab

Now use the color from textColorPrimary based on
current theme.

Bug: 32592245
Test: Visual
Change-Id: If6bbfe3b39ba30d96fc1f7d810472dc87006c3ea

res/color/sliding_tab_title_text_color.xml

@@ -17,6 +17,6 @@
 
 <selector xmlns:android="http://schemas.android.com/apk/res/android">
     <item android:state_selected="false"
-          android:color="#b3ffffff"/>
-    <item android:color="@android:color/white"/>
+          android:color="?android:attr/textColorSecondary"/>
+    <item android:color="?android:attr/textColorPrimary"/>
 </selector>

res/layout/dashboard_container_header.xml

@@ -16,10 +16,8 @@
 
 <com.android.settings.widget.SlidingTabLayout
     xmlns:android="http://schemas.android.com/apk/res/android"
-    xmlns:app="http://schemas.android.com/apk/res-auto"
     android:id="@+id/sliding_tabs"
     android:layout_width="match_parent"
     android:layout_height="wrap_content"
     android:layout_marginStart="@dimen/dashboard_header_margin_start"
-    android:layout_marginEnd="@dimen/dashboard_header_margin_end"
-    android:background="?android:attr/colorPrimary"/>
+    android:layout_marginEnd="@dimen/dashboard_header_margin_end"/>

res/layout/sliding_tab_title_view.xml

@@ -27,4 +27,5 @@
     android:maxLines="1"
     android:padding="@dimen/pager_tabs_title_padding"
     android:textColor="@color/sliding_tab_title_text_color"
-    android:textAllCaps="true"/>
+    android:textAllCaps="true"
+    android:theme="?android:attr/actionBarTheme"/>