Added registerChild; transforms, textures, glKey automatically handled.

BUG=skia:

Review URL: https://codereview.chromium.org/1266633003
diff --git a/src/gpu/effects/GrTextureDomain.h b/src/gpu/effects/GrTextureDomain.h
index 77c6ce3..7cf75d6 100644
--- a/src/gpu/effects/GrTextureDomain.h
+++ b/src/gpu/effects/GrTextureDomain.h
@@ -169,8 +169,6 @@
 
     const char* name() const override { return "TextureDomain"; }
 
-    void getGLProcessorKey(const GrGLSLCaps&, GrProcessorKeyBuilder*) const override;
-
     GrGLFragmentProcessor* createGLInstance() const override;
 
     const GrTextureDomain& textureDomain() const { return fTextureDomain; }
@@ -187,6 +185,8 @@
                           GrTextureParams::FilterMode,
                           GrCoordSet);
 
+    void onGetGLProcessorKey(const GrGLSLCaps&, GrProcessorKeyBuilder*) const override;
+
     bool onIsEqual(const GrFragmentProcessor&) const override;
 
     void onComputeInvariantOutput(GrInvariantOutput* inout) const override;