Available Trees:  

Mozilla DXR Source Code Index (version 0.1)

Search Syntax and Examples
simple string Search for a word or list of words separated by spaces.
Any bare words (e.g., not path:*) in the search are taken together.
Open nsAccessible::SetParent
path:name Return only results containing name in the path. Can be paired with ext:.
channel path:netwerk
type:name Find types that begin with or match name. Can be paired with member:.
Bare words are not allowed when doing type: searches.
type:nsIFile
derived:name Find types that derive from type named name.
Bare words are not allowed when doing derived: searches.
derived:nsIFile
member:name Find members that begin with or match name. Can be paired with type:.
Bare words are not allowed when doing member: searches.
member:CopyTo member:CopyTo type:nsLocalFile
macro:name Find macros that begin with or match name.
macro:ns_ensure
 

DXR was created by David Humphrey and is an experiment to use static analysis data from tools like
Dehydra in the context of a source code cross-reference. You can read more about it and watch a demo here.
It is an experimental system, and feedback or fixes are welcome.