android.os.Process: add killProcessGroup

Add Process.killProcessGroup to interface between ActivityManager and
libprocessgroup.

Bug: 15313911
Change-Id: I5226a6d86153b863e30d936cf1c84e256f0d7ea5
diff --git a/core/java/android/os/Process.java b/core/java/android/os/Process.java
index 86c749a..8caea25 100644
--- a/core/java/android/os/Process.java
+++ b/core/java/android/os/Process.java
@@ -1085,4 +1085,18 @@
          */
         public boolean usingWrapper;
     }
+
+    /**
+     * Kill all processes in a process group started for the given
+     * pid.
+     * @hide
+     */
+    public static final native int killProcessGroup(int uid, int pid);
+
+    /**
+     * Remove all process groups.  Expected to be called when ActivityManager
+     * is restarted.
+     * @hide
+     */
+    public static final native void removeAllProcessGroups();
 }