Show flags in Observatory.

Show flags in Observatory.

Add vm support for setting flags through vm service (UI coming soon).
e.g.
  http://127.0.0.1:8181/#/flags/set?name=some_flag&value=100

--

I reworked the Flags class to use a growing array rather than a linked list to store flags.  This means that we don't need to go through the hassle of building an array and sorting every time that we print/printjson.

R=johnmccutchan@google.com

Committed: https://code.google.com/p/dart/source/detail?r=36712

[Cutch, 2014-05-26 05:48:33]

lgtm w/ comments.

I worry about allowing flags to be changed at runtime that should only be
changed before initialization. I think we should create a whitelist of flags
that are safe to change via the service before 1.5 rolls.

https://codereview.chromium.org/299143007/diff/10013/runtime/vm/flags.cc
File runtime/vm/flags.cc (right):

https://codereview.chromium.org/299143007/diff/10013/runtime/vm/flags.cc#newc...
runtime/vm/flags.cc:108: flags_ = new Flag*[capacity_];
My preference would be for calloc / realloc.

https://codereview.chromium.org/299143007/diff/10013/runtime/vm/flags.cc#newc...
runtime/vm/flags.cc:111: Flag** new_flags = new Flag*[new_capacity];
realloc instead

https://codereview.chromium.org/299143007/diff/10013/runtime/vm/flags.cc#newc...
runtime/vm/flags.cc:115: delete flags_;
if you stick with new, this must be array delete:

delete[] flags_;

[turnidge, 2014-05-27 21:25:59]

As discussed offline, the flags/set functionality is not exposed in the UI yet.

https://codereview.chromium.org/299143007/diff/10013/runtime/vm/flags.cc
File runtime/vm/flags.cc (right):

https://codereview.chromium.org/299143007/diff/10013/runtime/vm/flags.cc#newc...
runtime/vm/flags.cc:115: delete flags_;
On 2014/05/26 05:48:33, Cutch wrote:
> if you stick with new, this must be array delete:
> 
> delete[] flags_;

Fixed delete.

Didn't go to realloc because I don't like realloc from a security standpoint (no
overflow protection).  Will reconsider if necessary.

[turnidge, 2014-05-27 21:27:36]

Committed patchset #3 manually as r36712 (presubmit successful).