Added trace query code and wired tracing through BrowserProxy so tests can run traces.

Added trace query code and wired tracing through BrowserProxy so tests can run traces.

This change:
- adds classes trace::Query and TraceAnalyzer to make it easy to search through trace data for specific events.
- adds Begin/EndTracing to BrowserProxy.
- adds "did it run on GPU" check to frame_rate_tests.cc using above features.

BUG=95714
TEST=base_unittests

[jbates, 2011-09-19 23:32:33]

This is a big one...

[nduca, 2011-09-20 16:52:34]

On 2011/09/19 23:32:33, jbates wrote:
> This is a big one...

Is there any way to tease this into a few smaller CLs? Typically, when I do
these I do one mega mega one like this to get it all working. Then break it
apart into smaller pieces  --- it takes longer, but it gets much better review
coverage that way.

[jbates, 2011-09-20 17:02:04]

On 2011/09/20 16:52:34, nduca wrote:
> On 2011/09/19 23:32:33, jbates wrote:
> > This is a big one...
> 
> Is there any way to tease this into a few smaller CLs? Typically, when I do
> these I do one mega mega one like this to get it all working. Then break it
> apart into smaller pieces  --- it takes longer, but it gets much better review
> coverage that way.

Absolutely, I'll split em up.