Roll src/third_party/skia/ 7869bbff2..e9573317d (7 commits).

https://chromium.googlesource.com/skia.git/+log/7869bbff26b7..e9573317d35d

$ git log 7869bbff2..e9573317d --date=short --no-merges --format='%ad %ae %s'
2016-01-25 bsalomon Make A8 readbacks work from non-A8 surfaces
2016-01-25 robertphillips Remove SkLerpXfermode
2016-01-25 msarett Revert of Initial support for turning Skia draws into a JSON document and vice versa. (patchset #3 id:80001 of https://codereview.chromium.org/1636563002/ )
2016-01-25 ethannicholas Initial support for turning Skia draws into a JSON document and vice versa. GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1636563002
2016-01-25 msarett Disable RAW test when SkRawCodec is not compiled
2016-01-25 benjaminwagner Add pre_log option to nanobench; make this option default true in nanobench_flags.py and dm_flags.py.
2016-01-25 bungeman Work around vs2013sp2-3 bug in skstd::unique_ptr.

CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel
TBR=msarett@google.com

Review URL: https://codereview.chromium.org/1631083003

Cr-Commit-Position: refs/heads/master@{#371403}

DEPS

@@ -39,7 +39,7 @@ vars = {
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling Skia
   # and whatever else without interference from each other.
-  'skia_revision': '7869bbff26b75a34ff8f56c9dfdaa98476adb6cb',
+  'skia_revision': 'e9573317d35d08254412eb407211f3607f8f74fb',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling V8
   # and whatever else without interference from each other.