Handle SCREEN_ON/OFF broadcasts without blocking.

NetworkPolicy currently uses a single background thread to process
various broadcasts.  When processing other broadcasts, this thread
can block our handling of SCREEN_ON/OFF, which are sent as ordered
broadcasts.

This change moves SCREEN_ON/OFF handling to the main thread, and
dispatches a one-way message to the background thread, allowing the
ordered broadcast to always proceed.

Bug: 6677047
Change-Id: I52de2c7b75beb8059bb87e123689ba4a9c4ae349

Author: jsharkey

services/java/com/android/server/net/NetworkPolicyManagerService.java

@@ -225,6 +225,7 @@ public class NetworkPolicyManagerService extends INetworkPolicyManager.Stub {
     private static final int MSG_LIMIT_REACHED = 5;
     private static final int MSG_RESTRICT_BACKGROUND_CHANGED = 6;
     private static final int MSG_ADVISE_PERSIST_THRESHOLD = 7;
+    private static final int MSG_SCREEN_ON_CHANGED = 8;
 
     private final Context mContext;
     private final IActivityManager mActivityManager;
@@ -349,7 +350,7 @@ public void systemReady() {
         final IntentFilter screenFilter = new IntentFilter();
         screenFilter.addAction(Intent.ACTION_SCREEN_ON);
         screenFilter.addAction(Intent.ACTION_SCREEN_OFF);
-        mContext.registerReceiver(mScreenReceiver, screenFilter, null, mHandler);
+        mContext.registerReceiver(mScreenReceiver, screenFilter);
 
         // watch for network interfaces to be claimed
         final IntentFilter connFilter = new IntentFilter(CONNECTIVITY_ACTION_IMMEDIATE);
@@ -411,7 +412,7 @@ public void onReceive(Context context, Intent intent) {
             synchronized (mRulesLock) {
                 // screen-related broadcasts are protected by system, no need
                 // for permissions check.
-                updateScreenOn();
+                mHandler.obtainMessage(MSG_SCREEN_ON_CHANGED).sendToTarget();
             }
         }
     };
@@ -1878,6 +1879,10 @@ public boolean handleMessage(Message msg) {
                     }
                     return true;
                 }
+                case MSG_SCREEN_ON_CHANGED: {
+                    updateScreenOn();
+                    return true;
+                }
                 default: {
                     return false;
                 }