Extensions: Switch to new permission message system, part V

extensions/common/permissions/api_permission.h

Index: extensions/common/permissions/api_permission.h
diff --git a/extensions/common/permissions/api_permission.h b/extensions/common/permissions/api_permission.h
index 28b7c97fdafbad59c32347dd6aef1086409034d2..444184af4a2a53b97747b06f37139c80df85cdf3 100644
--- a/extensions/common/permissions/api_permission.h
+++ b/extensions/common/permissions/api_permission.h
@@ -34,14 +34,17 @@ class APIPermission {
   // The IDs of all permissions available to apps. Add as many permissions here
   // as needed to generate meaningful permission messages. Add the rules for the
   // messages to ChromePermissionMessageProvider.
-  // Remove permissions from this list if they have no longer have a
-  // corresponding API permission and no permission message.
+  // Do not reorder this enumeration or remove any entries. If you need to add a
+  // new entry, add it just prior to kEnumBoundary.
   // TODO(sashab): Move this to a more central location, and rename it to
   // PermissionID.
   enum ID {
     // Error codes.
-    kInvalid = -2,
-    kUnknown = -1,
+    kInvalid,
+    kUnknown,
+
+    // For use in histograms.
+    kNone,

[Marc Treib, 2015/04/17 13:09:33]

Not quite sure about this: The existing histograms record a special "none" value
when an extension requires no permissions, or one value *per permission*
otherwise. So e.g. we can't just add all the numbers to get the total number of
installations. Maybe it'd be better to not have a "none" entry here, and instead
make separate bool histograms ("NeedsPermissions")?

[Devlin, 2015/04/27 17:58:03]

I agree - it's weird to have "None" as a unique permission type.  I like the
idea of a boolean histogram.  We should maintain the status quo for the
existing/legacy one, though.

[Marc Treib, 2015/04/28 12:31:32]

I've removed the "None" type for the new histograms, and instead added new
boolean "HasPermissions" histograms.

 
     // Real permissions.
     kAccessibilityFeaturesModify,
@@ -237,6 +240,9 @@ class APIPermission {
     kUsbDeviceUnknownProduct,
     kUsbDeviceUnknownVendor,
 
+    // Last entry: Add new entries above and ensure to update the
+    // "ExtensionPermission3" enum in tools/metrics/histograms/histograms.xml
+    // (by running update_extension_functions.py).
     kEnumBoundary
   };