Add functions for inspecting SkShader.

include/core/SkShader.h

Index: include/core/SkShader.h
diff --git a/include/core/SkShader.h b/include/core/SkShader.h
index 2f3764c0be032d9e566393fadebeda59bd1c3078..18716890b5463ba557f387968e17a573d5a55393 100644
--- a/include/core/SkShader.h
+++ b/include/core/SkShader.h
@@ -17,6 +17,7 @@
 
 class SkPath;
 class SkPicture;
+class SkXfermode;
 class GrContext;
 class GrEffectRef;
 
@@ -354,6 +355,20 @@ public:
     virtual GradientType asAGradient(GradientInfo* info) const;
 
     /**
+     *  If the shader subclass is composed of two shaders, return true, and if rec is not NULL,
+     *  fill it out with info about the shader.
+     */
+
+    struct ComposeRec {
+        const SkShader*     fShaderA;
+        const SkShader*     fShaderB;
+        const SkXfermode*   fMode;
+    };
+
+    virtual bool asACompose(ComposeRec* rec) const { return false; }
+
+
+    /**
      *  If the shader subclass has a GrEffect implementation, this resturns the effect to install.
      *  The incoming color to the effect has r=g=b=a all extracted from the SkPaint's alpha.
      *  The output color should be the computed SkShader premul color modulated by the incoming
@@ -362,6 +377,14 @@ public:
      */
     virtual GrEffectRef* asNewEffect(GrContext* context, const SkPaint& paint) const;
 
+#ifdef SK_BUILD_FOR_ANDROID_FRAMEWORK
+    /**
+     *  If the shader is a custom shader which has data the caller might want, call this function
+     *  to get that data.
+     */
+    virtual bool asACustomShader(void** customData) const { return false; }
+#endif
+
     //////////////////////////////////////////////////////////////////////////
     //  Factory methods for stock shaders