Alter SkXfermode's asFragmentProcessor & asXPFactory contracts

TBR=bsalomon@google.com

GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1674673002

Review URL: https://codereview.chromium.org/1674673002

4 files changed, 19 insertions, 37 deletions

diff --git a/include/client/android/SkAvoidXfermode.h b/include/client/android/SkAvoidXfermode.h
index 8d08827489..34deb8f02f 100644
--- a/include/client/android/SkAvoidXfermode.h
+++ b/include/client/android/SkAvoidXfermode.h
@@ -52,9 +52,9 @@ public:
                 const SkAlpha aa[]) const override;
 
 #if SK_SUPPORT_GPU
-    bool asFragmentProcessor(const GrFragmentProcessor** output,
-                             const GrFragmentProcessor* dst) const override;
-    bool asXPFactory(GrXPFactory** xpf) const override;
+    const GrFragmentProcessor* getFragmentProcessorForImageFilter(
+                                                    const GrFragmentProcessor* dst) const override;
+    GrXPFactory* asXPFactory() const override;
 #endif
 
     SK_TO_STRING_OVERRIDE()
diff --git a/include/client/android/SkPixelXorXfermode.h b/include/client/android/SkPixelXorXfermode.h
index 4aa78ccf5e..447bd81317 100644
--- a/include/client/android/SkPixelXorXfermode.h
+++ b/include/client/android/SkPixelXorXfermode.h
@@ -22,10 +22,9 @@ public:
     }
 
 #if SK_SUPPORT_GPU
-    bool asFragmentProcessor(const GrFragmentProcessor** output,
-                             const GrFragmentProcessor* dst) const override;
-
-    bool asXPFactory(GrXPFactory**) const override;
+    const GrFragmentProcessor* getFragmentProcessorForImageFilter(
+                                                    const GrFragmentProcessor* dst) const override;
+    GrXPFactory* asXPFactory() const override;
 #endif
 
     SK_TO_STRING_OVERRIDE()
diff --git a/include/core/SkXfermode.h b/include/core/SkXfermode.h
index 9549452960..76c57a51dd 100644
--- a/include/core/SkXfermode.h
+++ b/include/core/SkXfermode.h
@@ -194,37 +194,22 @@ public:
      */
     static bool IsOpaque(const SkXfermode* xfer, SrcColorOpacity opacityType);
 
-    /** Used to do in-shader blending between two colors computed in the shader via a
-        GrFragmentProcessor. The input to the returned FP is the src color. The dst color is
-        provided by the dst param which becomes a child FP of the returned FP. If the params are
-        null then this is just a query of whether the SkXfermode could support this functionality.
-        It is legal for the function to succeed but return a null output. This indicates that
+#if SK_SUPPORT_GPU
+    /** Used by the SkXfermodeImageFilter to blend two colors via a GrFragmentProcessor.
+        The input to the returned FP is the src color. The dst color is
+        provided by the dst param which becomes a child FP of the returned FP. 
+        It is legal for the function to return a null output. This indicates that
         the output of the blend is simply the src color.
      */
-    virtual bool asFragmentProcessor(const GrFragmentProcessor** output,
-                                     const GrFragmentProcessor* dst) const;
-
-    /** A subclass may implement this factory function to work with the GPU backend. It is legal
-      to call this with xpf NULL to simply test the return value. If xpf is non-NULL then the
-      xfermode may optionally allocate a factory to return to the caller as *xpf. The caller
-      will install it and own a ref to it. Since the xfermode may or may not assign *xpf, the
-      caller should set *xpf to NULL beforehand. XferProcessors cannot use a background texture.
-      */
-    virtual bool asXPFactory(GrXPFactory** xpf) const;
+    virtual const GrFragmentProcessor* getFragmentProcessorForImageFilter(
+                                                            const GrFragmentProcessor* dst) const;
 
-    /** Returns true if the xfermode can be expressed as an xfer processor factory (xpFactory).
-      This helper calls the asXPFactory() virtual. If the xfermode is NULL, it is treated as
-      kSrcOver_Mode. It is legal to call this with xpf param NULL to simply test the return value.
+    /** A subclass must implement this factory function to work with the GPU backend. 
+        The xfermode will return a factory for which the caller will get a ref. It is up 
+        to the caller to install it. XferProcessors cannot use a background texture.
       */
-    static inline bool AsXPFactory(SkXfermode* xfermode, GrXPFactory** xpf) {
-        if (nullptr == xfermode) {
-            if (xpf) {
-                *xpf = nullptr;
-            }
-            return true;
-        }
-        return xfermode->asXPFactory(xpf);
-    }
+    virtual GrXPFactory* asXPFactory() const;
+#endif
 
     SK_TO_STRING_PUREVIRT()
     SK_DECLARE_FLATTENABLE_REGISTRAR_GROUP()
diff --git a/include/effects/SkXfermodeImageFilter.h b/include/effects/SkXfermodeImageFilter.h
index d59b7a2b25..693425ed05 100644
--- a/include/effects/SkXfermodeImageFilter.h
+++ b/include/effects/SkXfermodeImageFilter.h
@@ -21,8 +21,6 @@ class SK_API SkXfermodeImageFilter : public SkImageFilter {
       */
 
 public:
-    virtual ~SkXfermodeImageFilter();
-
     static SkImageFilter* Create(SkXfermode* mode, SkImageFilter* background,
                                  SkImageFilter* foreground = NULL,
                                  const CropRect* cropRect = NULL) {
@@ -50,7 +48,7 @@ protected:
     void flatten(SkWriteBuffer&) const override;
 
 private:
-    SkXfermode* fMode;
+    SkAutoTUnref<SkXfermode> fMode;
     typedef SkImageFilter INHERITED;
 };