Add support to timeline for begin and end events

Add support to timeline for begin and end events

- Add support for begin and end even kinds.
- Update TimelineAnalysis to properly account for begin and end events as well as duration events.
- Add unit test for analysis of timelines with begin and end events.

R=rmacnak@google.com

Committed: https://github.com/dart-lang/sdk/commit/979b7868ca905e581d5f7a68891f3e83f0a81aad

[Cutch, 2015-10-06 22:23:29]

johnmccutchan@google.com changed reviewers:
+ rmacnak@google.com

[rmacnak, 2015-10-07 16:49:40]

https://codereview.chromium.org/1386263002/diff/40001/runtime/vm/timeline_ana...
File runtime/vm/timeline_analysis.cc (right):

https://codereview.chromium.org/1386263002/diff/40001/runtime/vm/timeline_ana...
runtime/vm/timeline_analysis.cc:350: if (!event->IsFinishedDuration() &&
!event->IsBeginOrEnd()) {
Would be clearer as

if (event->IsFinishedDuration()) {
  ...
} else if (event->IsBeginOrEnd()) {
  ...
} else {
  // Skip other event kinds.
}

https://codereview.chromium.org/1386263002/diff/40001/runtime/vm/timeline_tes...
File runtime/vm/timeline_test.cc (right):

https://codereview.chromium.org/1386263002/diff/40001/runtime/vm/timeline_tes...
runtime/vm/timeline_test.cc:828: }
Case with unpaired begin or end?

[Cutch, 2015-10-07 16:59:02]

https://codereview.chromium.org/1386263002/diff/40001/runtime/vm/timeline_ana...
File runtime/vm/timeline_analysis.cc (right):

https://codereview.chromium.org/1386263002/diff/40001/runtime/vm/timeline_ana...
runtime/vm/timeline_analysis.cc:350: if (!event->IsFinishedDuration() &&
!event->IsBeginOrEnd()) {
On 2015/10/07 16:49:40, rmacnak wrote:
> Would be clearer as
> 
> if (event->IsFinishedDuration()) {
>   ...
> } else if (event->IsBeginOrEnd()) {
>   ...
> } else {
>   // Skip other event kinds.
> }

Done.

https://codereview.chromium.org/1386263002/diff/40001/runtime/vm/timeline_tes...
File runtime/vm/timeline_test.cc (right):

https://codereview.chromium.org/1386263002/diff/40001/runtime/vm/timeline_tes...
runtime/vm/timeline_test.cc:828: }
On 2015/10/07 16:49:40, rmacnak wrote:
> Case with unpaired begin or end?

Done.

[rmacnak, 2015-10-07 17:00:45]

lgtm

[Cutch, 2015-10-07 21:11:48]

Committed patchset #4 (id:60001) manually as
979b7868ca905e581d5f7a68891f3e83f0a81aad (presubmit successful).