Reduce button presses to get a specific presetted trace

Users of tracing many times uses predefined preset modes e.g.
Web Developer, Frame Viewer, Input Latency etc.
This involves pressing 'Record', then choosing the preset option
from dropdown and then pressing Record button.

Instead we can list presets as options, where clicking on the preset
starts recording with the pre-defined trace categories. Only if we
choose "manual settings" mode, we need to press Record button.

The UX changes of this CL are as per the wireframes suggested by pdr
in the document:
https://docs.google.com/a/chromium.org/drawings/d/1fTlQyI2vdJoVzMqmdX9qRQsZIdJ1zzz_FCCEKfJ5S8M/edit

BUG=603

R=nduca,dsinclair,pdr
Correct the categories-expanded classlist behavior.

CL 667 modified the UX of the Record Selection dialog.
Committed CL had couple of minor issues:
1. If last selected value was 'Manual', on next invocation
   of record dialog, though the categories view was expanded
   the 'Edit categories' arrow was shown not expanded.
2. If user clicked on 'Edit categories' on a preset option,
   and then chooses another preset option, the 'Edit categories'
   was still open though it shouldn't be.

Both the issues are fixed in this CL.

BUG=603

R=dsinclair