[tools] Incrementally keep track of GC NVP output

[tools] Incrementally keep track of GC NVP output

We not keep track of the histogram as we process values and do not wait until
printing the histogram. Furthermore processing the histogram is not O(n) for n
values.

BUG=

Committed: https://crrev.com/307cc458b41c706dcf79969bb6f937f8311fb7e9
Cr-Commit-Position: refs/heads/master@{#30891}

[Michael Lippautz, 2015-09-23 13:17:32]

mlippautz@chromium.org changed reviewers:
+ hpayer@chromium.org

[Michael Lippautz, 2015-09-23 13:17:33]

Using this approach I could easily process the ~500MB output log.

[Hannes Payer (out of office), 2015-09-23 13:18:04]

lgtm

[Michael Lippautz, 2015-09-23 13:29:34]

The CQ bit was checked by mlippautz@chromium.org

[commit-bot: I haz the power, 2015-09-23 13:29:42]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1364733002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1364733002/20001

[commit-bot: I haz the power, 2015-09-23 13:52:41]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-09-23 13:52:57]

Patchset 2 (id:??) landed as
https://crrev.com/307cc458b41c706dcf79969bb6f937f8311fb7e9
Cr-Commit-Position: refs/heads/master@{#30891}