Add units to memory allocator dump attributes

Add units to memory allocator dump attributes

This patch aligns the attributes used by memory allocator dumps with
telemetry values
(https://code.google.com/p/chromium/codesearch#chromium/src/tools/telemetry/telemetry/value/__init__.py)
by introducing a 'units' field. This leads to the following
transformation:

  ScalarAttribute(x) -> ScalarAttribute('objects', x)
  BytesAttribute(x)  -> ScalarAttribute('bytes', x)

This patch also renames the allocated_objects_count field to
objects_count.

BUG=#849
R=nduca@chromium.org, primiano@chromium.org

Committed: https://chromium.googlesource.com/external/trace-viewer/+/ba605a208707d32e80f630ea0d0ecef61cd6cb7e

[petrcermak, 2015-04-27 12:34:46]

Hi, please review this patch.

Thanks,
Petr

[primiano, 2015-04-27 12:53:46]

Makes sense, LGTM.

[petrcermak, 2015-04-27 14:41:45]

Hi Nat, please review this change, which modifies the memory allocator dump
attributes to be more aligned with telemetry values by adding *units* to scalar
values.

(90% of the patch are unit test changes)

Thanks,
Petr

[nduca, 2015-04-27 14:44:33]

lgtm

[petrcermak, 2015-04-27 14:48:03]

Committed patchset #1 (id:1) manually as
ba605a208707d32e80f630ea0d0ecef61cd6cb7e (presubmit successful).