Set the pid of ProcessProfileRecord for system_server

Bug: 190084282
Test: Manual - Capture system heap dump, verify notification is posted
Change-Id: I53e05a644280add45b268c96bdcc74727e4f8ca3

services/core/java/com/android/server/am/ActivityManagerService.java

@@ -1804,8 +1804,7 @@ public class ActivityManagerService extends IActivityManager.Stub
                         0,
                         new HostingRecord("system"));
                 app.setPersistent(true);
-                app.mPid = MY_PID;
-                app.getWindowProcessController().setPid(MY_PID);
+                app.setPid(MY_PID);
                 app.mState.setMaxAdj(ProcessList.SYSTEM_ADJ);
                 app.makeActive(mSystemThread.getApplicationThread(), mProcessStats);
                 addPidLocked(app);