Fix the scrolling problems in homepage

- Remove the deprecated API and parameter usages of setting system ui
  visibility, which make the app bar scrolling behavior abnormal when
  the navigation bar is enabled.
- Remove the duplicate navigationBarColor of the homepage theme since
  Theme.Settings has configured it.
- Remove the unused scroll flags in search bar layout since its parent
  is no longer AppBarLayout.

Test: visual, robotest
Fixes: 178497625
Fixes: 179122861
Change-Id: I91537cff4f3d98e4bc31e6e42d23895df312fbd4

res/layout/search_bar.xml

@@ -17,14 +17,12 @@
 
 <LinearLayout
     xmlns:android="http://schemas.android.com/apk/res/android"
-    xmlns:app="http://schemas.android.com/apk/res-auto"
     android:layout_width="match_parent"
     android:layout_height="wrap_content"
     android:layout_marginTop="@dimen/search_bar_margin"
     android:layout_marginStart="@dimen/search_bar_margin"
     android:layout_marginEnd="@dimen/search_bar_margin"
-    android:layout_marginBottom="@dimen/search_bar_margin_bottom"
-    app:layout_scrollFlags="scroll|enterAlways">
+    android:layout_marginBottom="@dimen/search_bar_margin_bottom">
 
     <com.google.android.material.card.MaterialCardView
         android:id="@+id/search_bar"

res/values/themes.xml

@@ -221,7 +221,6 @@
         <item name="colorPrimaryDark">@*android:color/primary_dark_device_default_settings_light</item>
         <item name="android:windowLightStatusBar">true</item>
         <item name="android:navigationBarDividerColor">@*android:color/ripple_material_light</item>
-        <item name="android:navigationBarColor">@android:color/transparent</item>
     </style>
 
     <style name="Theme.Settings.ContextualCard" parent="Theme.Settings.Home">

src/com/android/settings/homepage/SettingsHomepageActivity.java

@@ -46,11 +46,7 @@ public class SettingsHomepageActivity extends FragmentActivity {
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
-
         setContentView(R.layout.settings_homepage_container);
-        final View root = findViewById(R.id.settings_homepage_container);
-        root.setSystemUiVisibility(
-                View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION | View.SYSTEM_UI_FLAG_LAYOUT_STABLE);
 
         final View appBar = findViewById(R.id.app_bar_container);
         appBar.setMinimumHeight(getSearchBoxHeight());