Refactor how we store and use samplers in Ganesh

src/effects/SkTableColorFilter.cpp

Index: src/effects/SkTableColorFilter.cpp
diff --git a/src/effects/SkTableColorFilter.cpp b/src/effects/SkTableColorFilter.cpp
index 0994097e6a23a257b109d689ffaedb9d343949a8..d5674fd7a08e8bc42051734341bb62f66803951a 100644
--- a/src/effects/SkTableColorFilter.cpp
+++ b/src/effects/SkTableColorFilter.cpp
@@ -434,25 +434,26 @@ void GLColorTableEffect::emitCode(EmitArgs& args) {
     }
 
     SkString coord;
+    const GrGLSLSampler& sampler = args.fUniformHandler->getSampler(args.fTexSamplers[0]);
 
     fragBuilder->codeAppendf("\t\t%s.a = ", args.fOutputColor);
     coord.printf("vec2(coord.a, %s.a)", yoffsets);
-    fragBuilder->appendTextureLookup(args.fTexSamplers[0], coord.c_str());
+    fragBuilder->appendTextureLookup(sampler, coord.c_str());
     fragBuilder->codeAppend(".a;\n");
 
     fragBuilder->codeAppendf("\t\t%s.r = ", args.fOutputColor);
     coord.printf("vec2(coord.r, %s.r)", yoffsets);
-    fragBuilder->appendTextureLookup(args.fTexSamplers[0], coord.c_str());
+    fragBuilder->appendTextureLookup(sampler, coord.c_str());
     fragBuilder->codeAppend(".a;\n");
 
     fragBuilder->codeAppendf("\t\t%s.g = ", args.fOutputColor);
     coord.printf("vec2(coord.g, %s.g)", yoffsets);
-    fragBuilder->appendTextureLookup(args.fTexSamplers[0], coord.c_str());
+    fragBuilder->appendTextureLookup(sampler, coord.c_str());
     fragBuilder->codeAppend(".a;\n");
 
     fragBuilder->codeAppendf("\t\t%s.b = ", args.fOutputColor);
     coord.printf("vec2(coord.b, %s.b)", yoffsets);
-    fragBuilder->appendTextureLookup(args.fTexSamplers[0], coord.c_str());
+    fragBuilder->appendTextureLookup(sampler, coord.c_str());
     fragBuilder->codeAppend(".a;\n");
 
     fragBuilder->codeAppendf("\t\t%s.rgb *= %s.a;\n", args.fOutputColor, args.fOutputColor);