SystemUI: fix transparent navigation bar keys in secondary display

Huge thanks to luka177 for investigation

What happens here is simple: mContext has Theme.SystemUI set, for
secondary displays, it uses createDisplayContext() which unsets Theme
because it's not a UI context. If we manually set theme again, resources
start resolving again and navigation bar keys are no longer transparent.

Dhina17: Ported to 14 QPR2

Change-Id: Ib8c9212ac0facda8e0f4eeac2d4f839748178cc9

packages/SystemUI/src/com/android/systemui/navigationbar/NavigationBarControllerImpl.java

@@ -35,6 +35,7 @@ import android.provider.Settings;
 import android.util.Log;
 import android.util.SparseArray;
 import android.util.SparseBooleanArray;
+import android.view.ContextThemeWrapper;
 import android.view.Display;
 import android.view.IWindowManager;
 import android.view.View;
@@ -396,9 +397,14 @@ public class NavigationBarControllerImpl implements
             return;
         }
 
-        final Context context = isOnDefaultDisplay
-                ? mContext
-                : mContext.createDisplayContext(display);
+        final Context context;
+        if (isOnDefaultDisplay) {
+            context = mContext;
+        } else {
+            Context rawContext = mContext.createDisplayContext(display);
+            context = new ContextThemeWrapper(rawContext,
+                com.android.systemui.res.R.style.Theme_SystemUI);
+        }
         NavigationBarComponent component = mNavigationBarComponentFactory.create(
                 context, savedState);
         NavigationBar navBar = component.getNavigationBar();