Delay discovery of system trust agents

Waits for BOOT_COMPLETED when enabling system trust agents.
This fixes an issue where no agents were discovered because the
packages were not ready after an OTA.

Bug: 18065140
Change-Id: Ibff9948e1536e07f868d6b29f432923a137091e6
diff --git a/services/core/java/com/android/server/trust/TrustManagerService.java b/services/core/java/com/android/server/trust/TrustManagerService.java
index fefbe0a..f9b1704 100644
--- a/services/core/java/com/android/server/trust/TrustManagerService.java
+++ b/services/core/java/com/android/server/trust/TrustManagerService.java
@@ -120,8 +120,9 @@
         if (phase == SystemService.PHASE_SYSTEM_SERVICES_READY && !isSafeMode()) {
             mPackageMonitor.register(mContext, mHandler.getLooper(), UserHandle.ALL, true);
             mReceiver.register(mContext);
-            maybeEnableFactoryTrustAgents(mLockPatternUtils, UserHandle.USER_OWNER);
             refreshAgentList(UserHandle.USER_ALL);
+        } else if (phase == SystemService.PHASE_BOOT_COMPLETED && !isSafeMode()) {
+            maybeEnableFactoryTrustAgents(mLockPatternUtils, UserHandle.USER_OWNER);
         }
     }