Changes from WebPagetest 2.14:

There are quite a few big additions/improvements in this release:

The addition of custom metrics.
Logs integration for test results.
Significant improvements to the new mobile agents.
The mobitest android agents are no longer supported (security concerns with the results processing).
Added support for capturing and viewing Chrome traces.

Web Server

Added support for writing test results to a log file (see logTestResults and logTestRequests in settings.ini.sample)
Significant improvements to the processing of mobile video captures.
Fixed the display of console log messages from mobile tests.
Fixed the waterfall translucency slider support in filmstrip view for Chrome 30+.
Improved test reliability (reduced instances of corrupt results).
Added sample benchmark configurations.
Fixed timeline processing for Chrome 36+.
Added support for viewing Chrome traces.
Added installer checks for php's memory limit, for tmp being on tmpfs and for being able to write to the dat directory.

Significant improvements to video and waterfall processing (done on the server but mobile-specific).
Changed the logic to close the browser between first and repeat view to match desktop testing.
Added support for running against an emulator (though it is very much not recommended for anything but dev).

Added support for capturing Chrome traces.
Fixed support for multi-step tests.
Fixed the reporting of HTTPS 204 responses.
Added support for overrideHost, setHeader and addHeader commands for IE HTTPS testing.
Improved the support for the exec and execAndWait commands in Chrome so they no longer run in a sandbox and can access the page variables.
Added support for capturing the page title and titleTime for Chrome (already worked for IE and Firefox).

No significant changes (will eventually be deprecated and replaced by wptdriver).