Last night, Google hosted a Campfire One event introducing Google Web Toolkit (GWT) 2.0. The Campfire event is divided into six segments that are all available on YouTube.
Then in Part 5, Kelly Norton introduces Speed Tracer, which is a Chrome extension that gives an unprecedented amount of insight into what Chrome is doing when it runs a web application. It is more similar to dynaTrace than it is to Firebug. Page Tracer is informative and so snappy that you might not believe the UI is written in HTML5 -- try it out!
However, my one gripe with the Campfire presentation is that you might come away from it believing that Speed Tracer works only with GWT applications, but that is not the case at all! Although its documentation lives under GWT on code.google.com and Speed Tracer was written using GWT, it can be downloaded and used completely independently from GWT. This morning, I installed it to explore the performance of some webapps I used to work on (which were written using Closure), such as Google Tasks. (I found some areas for improvement which I forwarded to the team.) I strongly recommend evaluating your own web applications using Speed Tracer as you may be surprised at what you discover.
Also, if you're like me, you may not notice the links to additional Speed Tracer documentation because they appear below the fold on the landing page. Under the Tools heading in the left-hand-nav, there are links to Hints, the Data Dump Format, and the Logging API.
If you stop and think about it, this level of tool support is essential for the Chrome OS initiative to succeed. If the browser is going to substitute for the desktop as a platform, then it must be fast (which is where Chrome comes in), it needs to have a kickass API (which is where HTML5 comes in), and it needs to have best-of-breed developer tools (which is where GWT, Closure, and Speed Tracer come in) so it is possible to build web applications that can compete with (and ideally exceed) desktop applications. When Chrome OS was originally announced, I was a naysayer, but now that more of the pieces are starting to come together, I'm getting a bit more optimistic.