Allocate isolated UID ranges for app zygote and its children.

Introduce a new range of app-zygote isolated UIDs, [90000..98999].
For each app that uses an application Zygote, allocate a range of
100 isolated UIDs. The application Zygote for an app will get a
UID out of that range, and all other children that are forked
from that zygote will get a UID from the same range.

Bug:  111434506
Test: app Zygote and its children run in the new range of
      isolated UIDs (with SELinux disabled). New set of
      tests for UID allocators pass.

Change-Id: I7a6883a5ddb95683932c93ea77f4e52d8f37fa4f
diff --git a/services/core/java/com/android/server/am/ProcessRecord.java b/services/core/java/com/android/server/am/ProcessRecord.java
index 6f0a562..0d0824a 100644
--- a/services/core/java/com/android/server/am/ProcessRecord.java
+++ b/services/core/java/com/android/server/am/ProcessRecord.java
@@ -76,6 +76,7 @@
     private final ActivityManagerService mService; // where we came from
     final ApplicationInfo info; // all about the first app in the process
     final boolean isolated;     // true if this is a special isolated process
+    final boolean appZygote;    // true if this is forked from the app zygote
     final int uid;              // uid of process; may be different from 'info' if isolated
     final int userId;           // user of process.
     final String processName;   // name of the process
@@ -559,6 +560,8 @@
         mService = _service;
         info = _info;
         isolated = _info.uid != _uid;
+        appZygote = (UserHandle.getAppId(_uid) >= Process.FIRST_APP_ZYGOTE_ISOLATED_UID
+                && UserHandle.getAppId(_uid) <= Process.LAST_APP_ZYGOTE_ISOLATED_UID);
         uid = _uid;
         userId = UserHandle.getUserId(_uid);
         processName = _processName;