Add dest type hint to SkShader::ContextRec

Let SkBlitter decide which dst type is optimal (PMColor vs PM4f), and
pass that info to shaders.

R=reed@google.com
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1724503002

Review URL: https://codereview.chromium.org/1724503002

1 files changed, 2 insertions, 0 deletions

diff --git a/src/core/SkBlitter.h b/src/core/SkBlitter.h
index 5740a5eaed..8711f1a10f 100644
--- a/src/core/SkBlitter.h
+++ b/src/core/SkBlitter.h
@@ -137,6 +137,8 @@ public:
                                    SkTBlitterAllocator*);
     ///@}
 
+    static SkShader::ContextRec::DstType PreferredShaderDest(const SkImageInfo&);
+
 protected:
     SkAutoMalloc fBlitMemory;
 };