Use Activity resources in DecorContext

We use the application context in DecorContext to avoid holding a reference
to the Activity. However, the resources don't match the Activity's in a multi-window
world, so we use the resources from the Activity, which  get updated as the Activity
goes between multi-window states. This avoids holding a reference to the Activity.

Bug:28096052
Change-Id: I2804f2420afad6dcecc56e5dece008c390540d72

core/java/com/android/internal/policy/DecorContext.java

@@ -17,22 +17,27 @@
 package com.android.internal.policy;
 
 import android.content.Context;
+import android.content.res.AssetManager;
+import android.content.res.Resources;
 import android.view.ContextThemeWrapper;
 import android.view.WindowManager;
 import android.view.WindowManagerImpl;
 
 /**
  * Context for decor views which can be seeded with pure application context and not depend on the
- * activity, but still provide some of the facilities that Activity has, e.g. themes.
+ * activity, but still provide some of the facilities that Activity has,
+ * e.g. themes, activity-based resources, etc.
  *
  * @hide
  */
 class DecorContext extends ContextThemeWrapper {
     private PhoneWindow mPhoneWindow;
     private WindowManager mWindowManager;
+    private Resources mActivityResources;
 
-    public DecorContext(Context context) {
+    public DecorContext(Context context, Resources activityResources) {
         super(context, null);
+        mActivityResources = activityResources;
     }
 
     void setPhoneWindow(PhoneWindow phoneWindow) {
@@ -52,4 +57,14 @@ class DecorContext extends ContextThemeWrapper {
         }
         return super.getSystemService(name);
     }
+
+    @Override
+    public Resources getResources() {
+        return mActivityResources;
+    }
+
+    @Override
+    public AssetManager getAssets() {
+        return mActivityResources.getAssets();
+    }
 }

core/java/com/android/internal/policy/PhoneWindow.java

@@ -2297,7 +2297,7 @@ public class PhoneWindow extends Window implements MenuBuilder.Callback {
             if (applicationContext == null) {
                 context = getContext();
             } else {
-                context = new DecorContext(applicationContext);
+                context = new DecorContext(applicationContext, getContext().getResources());
                 if (mTheme != -1) {
                     context.setTheme(mTheme);
                 }