[Extensions] Log instances of invalid extensions being added

extensions/common/manifest.h

Index: extensions/common/manifest.h
diff --git a/extensions/common/manifest.h b/extensions/common/manifest.h
index 5455cc6a7acb900c838d29bf844ce7b1fbca9869..f21713ad7dd6aeb328d924557f4821b2d0b6e9c6 100644
--- a/extensions/common/manifest.h
+++ b/extensions/common/manifest.h
@@ -110,6 +110,10 @@ class Manifest {
     return location == COMPONENT || location == EXTERNAL_COMPONENT;
   }
 
+  static inline bool IsValidLocation(Location location) {
+    return location > INVALID_LOCATION && location < NUM_LOCATIONS;
+  }
+
   // Unpacked extensions start off with file access since they are a developer
   // feature.
   static inline bool ShouldAlwaysAllowFileAccess(Location location) {