Use mContext directly, and enforce via logging

We already have the context saved, so we can just use that.
Add a log statement so we can test for the existence of this patch from
a CTS test.

Test: Edited code to force expection path to be called, confirmed
      reboot happens
Bug: 138952436
Bug: 140111727
Bug: 144312171

Change-Id: Iaceec82d4716837158d1233400b4a44cbf67a5e8
Merged-In: Iaceec82d4716837158d1233400b4a44cbf67a5e8

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

@@ -5276,11 +5276,14 @@ public class ActivityManagerService extends IActivityManager.Stub
 
         // Inform checkpointing systems of success
         try {
+            // This line is needed to CTS test for the correct exception handling
+            // See b/138952436#comment36 for context
+            Slog.i(TAG, "About to commit checkpoint");
             IStorageManager storageManager = PackageHelper.getStorageManager();
             storageManager.commitChanges();
         } catch (Exception e) {
             PowerManager pm = (PowerManager)
-                     mInjector.getContext().getSystemService(Context.POWER_SERVICE);
+                     mContext.getSystemService(Context.POWER_SERVICE);
             pm.reboot("Checkpoint commit failed");
         }