Add ContextRec param to SkShader::contextSize()

include/core/SkShader.h

Index: include/core/SkShader.h
diff --git a/include/core/SkShader.h b/include/core/SkShader.h
index 36256f6f09e4e73cc9d7e22d31982e6b1aecfc07..39715326d7e3e1f36d083c65ea07690dbcb79cf8 100644
--- a/include/core/SkShader.h
+++ b/include/core/SkShader.h
@@ -10,6 +10,7 @@
 
 #include "SkBitmap.h"
 #include "SkFlattenable.h"
+#include "SkImageInfo.h"
 #include "SkMask.h"
 #include "SkMatrix.h"
 #include "SkPaint.h"
@@ -96,14 +97,19 @@ public:
      *  ContextRec acts as a parameter bundle for creating Contexts.
      */
     struct ContextRec {
-        ContextRec(const SkPaint& paint, const SkMatrix& matrix, const SkMatrix* localM)
+        ContextRec(const SkPaint& paint, const SkMatrix& matrix, const SkMatrix* localM,
+                   SkColorType devColorType, SkColorProfileType devColorProfile)
             : fPaint(&paint)
             , fMatrix(&matrix)
-            , fLocalMatrix(localM) {}
+            , fLocalMatrix(localM)
+            , fDeviceColorType(devColorType)
+            , fDeviceColorProfile(devColorProfile) {}
 
         const SkPaint*  fPaint;         // the current paint associated with the draw
         const SkMatrix* fMatrix;        // the current matrix in the canvas
         const SkMatrix* fLocalMatrix;   // optional local matrix
+        const SkColorType        fDeviceColorType;
+        const SkColorProfileType fDeviceColorProfile;

[f(malita), 2016/02/22 16:09:50]

I'm kinda torn on pushing explicit dst color info to the shaders - it means
they'll likely end up duplicating some of SkBlitter's heuristics in deciding
whether to optimize for 4b or 4f.

SkBlitter should know which shadeSpan method is going to use, so maybe a more
assertive

bool fWillCallShadeSpan4f;

would provide less footgun?

[f(malita), 2016/02/22 17:08:23]

PS#2 implements this alternative approach, replacing the color info with a
preferred-dst-type computed in SkBlitter.

PTAL

     };
 
     class Context : public ::SkNoncopyable {
@@ -188,7 +194,7 @@ public:
      *  Override this if your subclass overrides createContext, to return the correct size of
      *  your subclass' context.
      */
-    virtual size_t contextSize() const;
+    virtual size_t contextSize(const ContextRec&) const;
 
     /**
      *  Returns true if this shader is just a bitmap, and if not null, returns the bitmap,