blitters for sRGB and float16

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1697863002

Review URL: https://codereview.chromium.org/1697863002
diff --git a/src/core/SkCoreBlitters.h b/src/core/SkCoreBlitters.h
index d2559f5..06e106d 100644
--- a/src/core/SkCoreBlitters.h
+++ b/src/core/SkCoreBlitters.h
@@ -49,6 +49,7 @@
     uint32_t            fShaderFlags;
     const SkShader*     fShader;
     SkShader::Context*  fShaderContext;
+    bool                fConstInY;
 
 private:
     // illegal
@@ -177,7 +178,6 @@
     SkBlitRow::Proc32   fProc32;
     SkBlitRow::Proc32   fProc32Blend;
     bool                fShadeDirectlyIntoDevice;
-    bool                fConstInY;
     
     // illegal
     SkARGB32_Shader_Blitter& operator=(const SkARGB32_Shader_Blitter&);
@@ -185,29 +185,13 @@
     typedef SkShaderBlitter INHERITED;
 };
 
-class SkARGB32_Shader4f_Blitter : public SkARGB32_Shader_Blitter {
-public:
-    SkARGB32_Shader4f_Blitter(const SkPixmap& device, const SkPaint& paint,
-                              SkShader::Context* shaderContext);
-    virtual ~SkARGB32_Shader4f_Blitter();
-    void blitH(int x, int y, int width) override;
-    void blitV(int x, int y, int height, SkAlpha alpha) override;
-    void blitRect(int x, int y, int width, int height) override;
-    void blitAntiH(int x, int y, const SkAlpha[], const int16_t[]) override;
-    void blitMask(const SkMask&, const SkIRect&) override;
-    
-private:
-    SkXfermode::PM4fState   fState;
-    SkXfermode::PM4fProc1   fProc1;
-    SkXfermode::PM4fProcN   fProcN;
-    SkPM4f*                 fBuffer;
-    bool                    fConstInY;
-    
-    // illegal
-    SkARGB32_Shader4f_Blitter& operator=(const SkARGB32_Shader4f_Blitter&);
-    
-    typedef SkARGB32_Shader_Blitter INHERITED;
-};
+SkBlitter* SkBlitter_ARGB32_Create(const SkPixmap& device, const SkPaint& paint,
+                                   SkShader::Context* shaderContext,
+                                   SkTBlitterAllocator* allocator);
+
+SkBlitter* SkBlitter_ARGB64_Create(const SkPixmap& device, const SkPaint& paint,
+                                   SkShader::Context* shaderContext,
+                                   SkTBlitterAllocator* allocator);
 
 ///////////////////////////////////////////////////////////////////////////////