Roll external/skia a754378ef..ad15264f9 (10 commits)
https://skia.googlesource.com/skia.git/+log/a754378ef..ad15264f9
2017-05-02 reed@google.com fix tricolor shader
2017-05-02 jvanverth@google.com Remove translateZ and lights from SkCanvas
2017-05-02 bsalomon@google.com Revert "eliminated GrGLSLExpr"
2017-05-02 msarett@google.com Support numerical transfer functions in readPixels()
2017-05-02 msarett@google.com Add support for row-by-row jpeg encoding
2017-05-02 msarett@google.com Revert "Revert "Remove copyTo() legacy API flag from bzl""
2017-05-02 jvanverth@google.com Add wireframe mode to Viewer.
2017-05-02 ethannicholas@google.com eliminated GrGLSLExpr
2017-05-02 reed@google.com speedup exp() in gaussian colorfilter
2017-05-02 jbudorick@chromium.org Manually roll skia recipe deps.
Test: Presubmit checks will test this change.
Change-Id: I62d726a052fb01232b4d69ff9c5e1ebbda9718c8