Cleanup some of the thread merging.

Adds an optimization for checking whether a looper is stuck,
with a new Looper method to see if its thread is currently
idle.  This will allow us to put a large number of loopers
in the monitor efficiently, since we generally won't have to
do a context switch on each of them (since most looper threads
spend most of their time idle waiting for work).

Also change things so the system process's main thread
is actually running on the main thread.  Because Jeff
asked for this, and who am I to argue? :)

Change-Id: I12999e6f9c4b056c22dd652cb78c2453c391061f

services/java/com/android/server/SystemServer.java

@@ -75,7 +75,7 @@ import java.io.File;
 import java.util.Timer;
 import java.util.TimerTask;
 
-class ServerThread extends Thread {
+class ServerThread {
     private static final String TAG = "SystemServer";
     private static final String ENCRYPTING_STATE = "trigger_restart_min_framework";
     private static final String ENCRYPTED_STATE = "1";
@@ -87,8 +87,7 @@ class ServerThread extends Thread {
         Log.wtf(TAG, "BOOT FAILURE " + msg, e);
     }
 
-    @Override
-    public void run() {
+    public void initAndLoop() {
         EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_SYSTEM_RUN,
             SystemClock.uptimeMillis());
 
@@ -1119,8 +1118,10 @@ public class SystemServer {
 
     public static final void init2() {
         Slog.i(TAG, "Entered the Android system server!");
-        Thread thr = new ServerThread();
-        thr.setName("android.server.ServerThread");
-        thr.start();
+
+        // This used to be its own separate thread, but now it is
+        // just the loop we run on the main thread.
+        ServerThread thr = new ServerThread();
+        thr.initAndLoop();
     }
 }