The src directory contains Chromium source from the following locations:

    http://src.chromium.org/chrome/trunk/src/chrome/browser/resources/shared/
    http://src.chromium.org/chrome/trunk/src/chrome/browser/resources/tracing/

The file src/UPSTREAM_REVISION contains the upstream revision number that was
last pulled.  There may be local patches applied on top of the upstream source,
but we should keep those to a minimum.

The update.py script should be used to package the CSS and Javascript files in
the src directory into the style.css and script.js files.  These files are
being checked in, and get embedded in each trace HTML file the systrace.py
generates.  Each time a file in the www directory gets updated, this script
will need to be rerun, and the generated files must be committed along with the
changes to the www directory.