Fix minor undercounting in SkRecord::bytesUsed().

Fix minor undercounting in SkRecord::bytesUsed().

When an SkRecord has more than kInlineRecords ops in it (today, 5 or more), the
current logic undercounts the bytes used by the SkRecord by sizeof(Record) *
kInlineRecords, i.e. 32 bytes.  This isn't a huge deal... by the time you've
recorded 5 ops, we're typically up around 1KB anyway, and it's only ever off by
that constant 32 bytes, so somewhere between 3% to 0% error as the picture grows.

But now that I've noticed, we might as well fix it.  Basically, this is a
reminder that the inline space used to store those first kInlineRecords ops
goes to waste once we pass that threshold.  In contrast, fInlineAlloc, the
space we preallocate for the SkVarAlloc, never goes to waste.  It always holds
the first few ops' data even when we grow past it.

BUG=skia:

Committed: https://skia.googlesource.com/skia/+/1dda2194e0c3a486032b2dd4d3eaea67fa47d818

[mtklein_C, 2015-04-10 18:02:08]

mtklein@chromium.org changed reviewers:
+ reed@google.com

[mtklein_C, 2015-04-10 18:02:12]

The CQ bit was checked by mtklein@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-04-10 18:02:27]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1081433002/1

[commit-bot: I haz the power, 2015-04-10 18:11:42]

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

[commit-bot: I haz the power, 2015-04-10 18:11:42]

This issue passed the CQ dry run.

[mtklein, 2015-04-13 17:18:30]

mtklein@google.com changed reviewers:
+ mtklein@google.com

[mtklein, 2015-04-13 17:18:30]

added a comment

[reed1, 2015-04-13 18:05:11]

lgtm

[mtklein, 2015-04-13 18:21:21]

The CQ bit was checked by mtklein@google.com

[commit-bot: I haz the power, 2015-04-13 18:21:34]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1081433002/20001

[commit-bot: I haz the power, 2015-04-13 19:17:08]

Committed patchset #2 (id:20001) as
https://skia.googlesource.com/skia/+/1dda2194e0c3a486032b2dd4d3eaea67fa47d818