add SK_LEGACY_DRAWPICTURECALLBACK guard flag

add SK_LEGACY_DRAWPICTURECALLBACK guard flag

Used until chrome switches to the new skia api

BUG=
TBR=robertphilips@chromium.org

Committed: https://crrev.com/c97047888c9e13602ee390c99fd78b05efe7bc26
Cr-Commit-Position: refs/heads/master@{#320830}

[reed1, 2015-03-16 21:10:28]

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

[reed1, 2015-03-16 21:10:39]

The CQ bit was checked by reed@google.com

[reed1, 2015-03-16 21:11:00]

... so we can remove this flag from skia_for_chromium_defines.gypi

[commit-bot: I haz the power, 2015-03-16 21:11:18]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1014473005/1

[commit-bot: I haz the power, 2015-03-17 00:29:49]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-17 00:30:27]

Patchset 1 (id:??) landed as
https://crrev.com/c97047888c9e13602ee390c99fd78b05efe7bc26
Cr-Commit-Position: refs/heads/master@{#320830}

[robertphillips, 2015-03-17 13:12:59]

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

[robertphillips, 2015-03-17 13:13:00]

lgtm

[robertphillips1, 2015-03-17 13:15:42]

lgtm