[tracing] Clean up the MemoryInfra API surface (1/3)

[tracing] Clean up the MemoryInfra API surface (1/3)

This patch simplifies the API surface of MemoryInfra switching
attribute names from std::string to char*.

The main goal is to make the dumping fast and predictable memory-wise.
There is no point allowing the attribute names to be arbitrary strings
(read non static "quoted" char* ptrs). That has the only effect of
causing loads of copies and std::string ctors / dtors.

This is part of a multisided dance:
 1 In this CL, the new char* overloads are being defined, temporarily side
   by side with the old std::string ones.
 2 Once Blink is rolled, chromium-side will switch from WebString -> char*.
 3 Once landed, blink side can remove the WebString overloads.

BUG=495628, 480500
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=196918

[Primiano Tucci (use gerrit), 2015-06-11 00:48:00]

primiano@chromium.org changed reviewers:
+ pdr@chromium.org, rbyers@chromium.org

[Primiano Tucci (use gerrit), 2015-06-11 00:48:01]

Hello!
I need to do some cleanup (crbug.com/495628) for motivations, and it will
require a 3 sided patch.
Can I ask you to review:

This CL:
crrev.com/1173253002

And the final cleanup CL:
crrev.com/1176223002

(I will find somebody for the chromium side:
crrev.com/1180733002 )

If it LGTY, please tick this one, so tomorrow in EMEA time I can land the other
two.
Thanks,
Primiano

[Rick Byers, 2015-06-11 01:38:29]

The CQ bit was checked by rbyers@chromium.org

[Rick Byers, 2015-06-11 01:38:29]

lgtm

[commit-bot: I haz the power, 2015-06-11 01:38:36]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1173253002/1

[commit-bot: I haz the power, 2015-06-11 02:20:40]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-06-11 02:20:41]

Try jobs failed on following builders:
  linux_blink_rel on tryserver.blink (JOB_FAILED,
http://build.chromium.org/p/tryserver.blink/builders/linux_blink_rel/builds/6...)

[Rick Byers, 2015-06-11 02:51:03]

On 2015/06/11 02:20:41, commit-bot: I haz the power wrote:
> Try jobs failed on following builders:
>   linux_blink_rel on tryserver.blink (JOB_FAILED,
>
http://build.chromium.org/p/tryserver.blink/builders/linux_blink_rel/builds/6...)

Sorry, try bots are horked right now - try again in the morning?

[Primiano Tucci (use gerrit), 2015-06-11 06:02:36]

The CQ bit was checked by primiano@chromium.org

[commit-bot: I haz the power, 2015-06-11 06:02:44]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1173253002/1

[commit-bot: I haz the power, 2015-06-11 06:50:54]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=196918