Print warning log for uses of -f/-F on non-ADB UID.

When an app executes the requestsync command with their own UID,
-f and -F cannot be used.

Let's log it on logcat to make it prominent. People often throw away
command output.

Change-Id: Ie0219e9bdea20edc290785f84a101bb546380136
Fixes: 78901672
Test: manual test
diff --git a/services/core/java/com/android/server/content/ContentService.java b/services/core/java/com/android/server/content/ContentService.java
index e840a29..03d8f39 100644
--- a/services/core/java/com/android/server/content/ContentService.java
+++ b/services/core/java/com/android/server/content/ContentService.java
@@ -1279,7 +1279,9 @@
                 case Process.SYSTEM_UID:
                     break; // Okay
                 default:
-                    throw new SecurityException("Invalid extras specified.");
+                    final String msg = "Invalid extras specified.";
+                    Log.w(TAG, msg + " requestsync -f/-F needs to run on 'adb shell'");
+                    throw new SecurityException(msg);
             }
         }
     }