NOT YET READY: UMA recording the kind of target frame when extensions pierce browsing instance.

extensions/common/manifest.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef EXTENSIONS_COMMON_MANIFEST_H_
 #define EXTENSIONS_COMMON_MANIFEST_H_
 
 #include <map>
 #include <memory>
 #include <set>
@@ skipping 34 matching lines @@
                          // policies), cached locally and installed from the
                          // cache.
     EXTERNAL_COMPONENT,  // Similar to COMPONENT in that it's considered an
                          // internal implementation detail of chrome, but
     // installed from an update URL like the *DOWNLOAD ones.
 
     // New enum values must go above here.
     NUM_LOCATIONS
   };
 
-  // Do not change the order of entries or remove entries in this list
-  // as this is used in UMA_HISTOGRAM_ENUMERATIONs about extensions.
+  // Do not change the order of entries or remove entries in this list as this
+  // is used in ExtensionType enum in tools/metrics/histograms/enums.xml.
   enum Type {
     TYPE_UNKNOWN = 0,
-    TYPE_EXTENSION,
-    TYPE_THEME,
-    TYPE_USER_SCRIPT,
-    TYPE_HOSTED_APP,
+    TYPE_EXTENSION = 1,
+    TYPE_THEME = 2,
+    TYPE_USER_SCRIPT = 3,
+    TYPE_HOSTED_APP = 4,
     // This is marked legacy because platform apps are preferred. For
     // backwards compatibility, we can't remove support for packaged apps
-    TYPE_LEGACY_PACKAGED_APP,
-    TYPE_PLATFORM_APP,
-    TYPE_SHARED_MODULE,
+    TYPE_LEGACY_PACKAGED_APP = 5,
+    TYPE_PLATFORM_APP = 6,
+    TYPE_SHARED_MODULE = 7,
 
     // New enum values must go above here.
-    NUM_LOAD_TYPES
+    TYPE_MAX = TYPE_SHARED_MODULE,
   };
 
   // Given two install sources, return the one which should take priority
   // over the other. If an extension is installed from two sources A and B,
   // its install source should be set to GetHigherPriorityLocation(A, B).
   static Location GetHigherPriorityLocation(Location loc1, Location loc2);
 
   // Whether the |location| is external or not.
   static inline bool IsExternalLocation(Location location) {
     return location == EXTERNAL_PREF ||
@@ skipping 117 matching lines @@
   std::unique_ptr<base::DictionaryValue> value_;
 
   Type type_;
 
   DISALLOW_COPY_AND_ASSIGN(Manifest);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_COMMON_MANIFEST_H_