Improve keying for theme caches, rebase system theme on config change

Themes now use an array of applied styles rather than a String to store
their history. They are keyed based on a hash code computed from the
history of applied styles. The themed drawable cache has been abstracted
out into its own class.

Also updates system context to use DayNight as the default and ensures
that GlobalActions uses the correct context, which exercises the change.

CTS tests have been added in another CL.

Bug: 20421157
Change-Id: I9eb4b7dffd198ad24d02f656eaf0839570b59caa

2 files changed, 9 insertions, 2 deletions

diff --git a/services/core/java/com/android/server/policy/GlobalActions.java b/services/core/java/com/android/server/policy/GlobalActions.java
index b431b33..3cee927 100644
--- a/services/core/java/com/android/server/policy/GlobalActions.java
+++ b/services/core/java/com/android/server/policy/GlobalActions.java
@@ -1138,7 +1138,7 @@ class GlobalActions implements DialogInterface.OnDismissListener, DialogInterfac
 
         public GlobalActionsDialog(Context context, AlertParams params) {
             super(context, getDialogTheme(context));
-            mContext = context;
+            mContext = getContext();
             mAlert = new AlertController(mContext, this, getWindow());
             mAdapter = (MyAdapter) params.mAdapter;
             mWindowTouchSlop = ViewConfiguration.get(context).getScaledWindowTouchSlop();
diff --git a/services/java/com/android/server/SystemServer.java b/services/java/com/android/server/SystemServer.java
index 2d265e2..925a609 100644
--- a/services/java/com/android/server/SystemServer.java
+++ b/services/java/com/android/server/SystemServer.java
@@ -28,6 +28,7 @@ import android.content.Context;
 import android.content.Intent;
 import android.content.pm.PackageManager;
 import android.content.res.Configuration;
+import android.content.res.Resources.Theme;
 import android.os.Build;
 import android.os.Environment;
 import android.os.FactoryTest;
@@ -291,7 +292,7 @@ public final class SystemServer {
     private void createSystemContext() {
         ActivityThread activityThread = ActivityThread.systemMain();
         mSystemContext = activityThread.getSystemContext();
-        mSystemContext.setTheme(android.R.style.Theme_DeviceDefault_Light_DarkActionBar);
+        mSystemContext.setTheme(android.R.style.Theme_Material_DayNight_DarkActionBar);
     }
 
     /**
@@ -1026,6 +1027,12 @@ public final class SystemServer {
         w.getDefaultDisplay().getMetrics(metrics);
         context.getResources().updateConfiguration(config, metrics);
 
+        // The system context's theme may be configuration-dependent.
+        final Theme systemTheme = context.getTheme();
+        if (systemTheme.getChangingConfigurations() != 0) {
+            systemTheme.rebase();
+        }
+
         try {
             // TODO: use boot phase
             mPowerManagerService.systemReady(mActivityManagerService.getAppOpsService());