Force activities to run on the second display for testing.

This is a simple hack for testing and development purposes.
It makes the framework place the main window of an activity
on to a secondary display instead of on the default display.

Set the "debug.second-display.pkg" to a substring of the
package name of the activity that you want to have show
up on the secondary display, such as "com.example.android.apis"

Bug: 7183618
Change-Id: I0a9e7f27c8ff253253b9de57d4bc49f31d95a0e2

Author: Jeff Brown

core/java/android/app/ActivityThread.java

@@ -65,6 +65,7 @@
 import android.os.ServiceManager;
 import android.os.StrictMode;
 import android.os.SystemClock;
+import android.os.SystemProperties;
 import android.os.Trace;
 import android.os.UserHandle;
 import android.util.AndroidRuntimeException;
@@ -2089,9 +2090,7 @@ private Activity performLaunchActivity(ActivityClientRecord r, Intent customInte
                     + ", dir=" + r.packageInfo.getAppDir());
 
             if (activity != null) {
-                ContextImpl appContext = new ContextImpl();
-                appContext.init(r.packageInfo, r.token, this);
-                appContext.setOuterContext(activity);
+                Context appContext = createBaseContextForActivity(r, activity);
                 CharSequence title = r.activityInfo.loadLabel(appContext.getPackageManager());
                 Configuration config = new Configuration(mCompatConfiguration);
                 if (DEBUG_CONFIGURATION) Slog.v(TAG, "Launching activity "
@@ -2156,6 +2155,31 @@ private Activity performLaunchActivity(ActivityClientRecord r, Intent customInte
         return activity;
     }
 
+    private Context createBaseContextForActivity(ActivityClientRecord r,
+            final Activity activity) {
+        ContextImpl appContext = new ContextImpl();
+        appContext.init(r.packageInfo, r.token, this);
+        appContext.setOuterContext(activity);
+
+        // For debugging purposes, if the activity's package name contains the value of
+        // the "debug.use-second-display" system property as a substring, then show
+        // its content on a secondary display if there is one.
+        Context baseContext = appContext;
+        String pkgName = SystemProperties.get("debug.second-display.pkg");
+        if (pkgName != null && !pkgName.isEmpty()
+                && r.packageInfo.mPackageName.contains(pkgName)) {
+            DisplayManagerGlobal dm = DisplayManagerGlobal.getInstance();
+            for (int displayId : dm.getDisplayIds()) {
+                if (displayId != Display.DEFAULT_DISPLAY) {
+                    Display display = dm.getRealDisplay(displayId);
+                    baseContext = appContext.createDisplayContext(display);
+                    break;
+                }
+            }
+        }
+        return baseContext;
+    }
+
     private void handleLaunchActivity(ActivityClientRecord r, Intent customIntent) {
         // If we are getting ready to gc after going to the background, well
         // we are back active so skip it.