Generate globally (cross-process) unique IDs for memory tracing dumps

Generate globally (cross-process) unique IDs for memory tracing dumps

Refactoring the hashing code to use it in memory_dump_manager to make
the guid unique.

BUG=462931
Committed: https://crrev.com/4498d8f0a9d899c638eb2c8be25bcb33cc4a2082
Cr-Commit-Position: refs/heads/master@{#325071}

[ssid, 2015-03-11 10:24:32]

ssid@chromium.org changed reviewers:
+ primiano@chromium.org

[ssid, 2015-03-11 10:24:32]

Is this what to be done?

[Primiano Tucci (use gerrit), 2015-04-13 22:13:57]

primiano@chromium.org changed reviewers:
+ dsinclair@chromium.org

[Primiano Tucci (use gerrit), 2015-04-13 22:13:58]

+dsinclair, can you PTAL to this ~10 lines CL?

Makes sense for me with 1 nit and one rename request, but I defer to whatever 
Dan thinks is better here.

https://codereview.chromium.org/994133002/diff/1/base/trace_event/memory_dump...
File base/trace_event/memory_dump_manager.cc (right):

https://codereview.chromium.org/994133002/diff/1/base/trace_event/memory_dump...
base/trace_event/memory_dump_manager.cc:109: const uint64 guid =
base::trace_event::TraceLog::GetInstance()->HashEventId(
nit: no need for base::trace_event as you are already in the namespace

https://codereview.chromium.org/994133002/diff/1/base/trace_event/trace_event...
File base/trace_event/trace_event_impl.h (right):

https://codereview.chromium.org/994133002/diff/1/base/trace_event/trace_event...
base/trace_event/trace_event_impl.h:605: uint64 HashEventId(uint64 id);
I think this should be called MangleEventId, but I defer to Dan here.

[dsinclair, 2015-04-14 13:42:46]

lgtm w/ nits fixed.

https://codereview.chromium.org/994133002/diff/1/base/trace_event/trace_event...
File base/trace_event/trace_event_impl.h (right):

https://codereview.chromium.org/994133002/diff/1/base/trace_event/trace_event...
base/trace_event/trace_event_impl.h:605: uint64 HashEventId(uint64 id);
On 2015/04/13 at 22:13:58, Primiano Tucci wrote:
> I think this should be called MangleEventId, but I defer to Dan here.

+1 we use mangle in other places in the trace event framework.

[ssid, 2015-04-14 16:50:20]

The CQ bit was checked by ssid@chromium.org

[ssid, 2015-04-14 16:50:20]

The patchset sent to the CQ was uploaded after l-g-t-m from
dsinclair@chromium.org
Link to the patchset: https://codereview.chromium.org/994133002/#ps20001 (title:
"Made changes.")

[commit-bot: I haz the power, 2015-04-14 16:51:11]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/994133002/20001

[commit-bot: I haz the power, 2015-04-14 16:55:53]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-04-14 16:56:37]

Patchset 2 (id:??) landed as
https://crrev.com/4498d8f0a9d899c638eb2c8be25bcb33cc4a2082
Cr-Commit-Position: refs/heads/master@{#325071}