Rename EmitArgs::fSamplers to fTexSamplers

Renames fSamplers to fTexSamplers in GrProcessor EmitArgs, and renames
GrGLSLTextureSampler to GrGLSLSampler. This will allow us to add a
second array of buffer samplers.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1862373003

Review URL: https://codereview.chromium.org/1862373003
diff --git a/experimental/SkPerlinNoiseShader2/SkPerlinNoiseShader2.cpp b/experimental/SkPerlinNoiseShader2/SkPerlinNoiseShader2.cpp
index 09762b3..42211e4 100644
--- a/experimental/SkPerlinNoiseShader2/SkPerlinNoiseShader2.cpp
+++ b/experimental/SkPerlinNoiseShader2/SkPerlinNoiseShader2.cpp
@@ -819,7 +819,7 @@
         xCoords.appendf("vec2(%s.x, 0.5)", floorVal);
 
         noiseCode.appendf("\n\tvec2 %s;\n\t%s.x = ", latticeIdx, latticeIdx);
-        fsBuilder->appendTextureLookup(&noiseCode, args.fSamplers[0], xCoords.c_str(),
+        fsBuilder->appendTextureLookup(&noiseCode, args.fTexSamplers[0], xCoords.c_str(),
                                        kVec2f_GrSLType);
         noiseCode.append(".r;");
     }
@@ -830,7 +830,7 @@
         xCoords.appendf("vec2(%s.z, 0.5)", floorVal);
 
         noiseCode.appendf("\n\t%s.y = ", latticeIdx);
-        fsBuilder->appendTextureLookup(&noiseCode, args.fSamplers[0], xCoords.c_str(),
+        fsBuilder->appendTextureLookup(&noiseCode, args.fTexSamplers[0], xCoords.c_str(),
                                        kVec2f_GrSLType);
         noiseCode.append(".r;");
     }
@@ -855,7 +855,7 @@
         SkString latticeCoords("");
         latticeCoords.appendf("vec2(%s.x, %s)", bcoords, chanCoord);
         noiseCode.appendf("\n\tvec4 %s = ", lattice);
-        fsBuilder->appendTextureLookup(&noiseCode, args.fSamplers[1], latticeCoords.c_str(),
+        fsBuilder->appendTextureLookup(&noiseCode, args.fTexSamplers[1], latticeCoords.c_str(),
             kVec2f_GrSLType);
         noiseCode.appendf(".bgra;\n\t%s.x = ", uv);
         noiseCode.appendf(dotLattice, lattice, lattice, inc8bit, fractVal);
@@ -867,7 +867,7 @@
         SkString latticeCoords("");
         latticeCoords.appendf("vec2(%s.y, %s)", bcoords, chanCoord);
         noiseCode.append("\n\tlattice = ");
-        fsBuilder->appendTextureLookup(&noiseCode, args.fSamplers[1], latticeCoords.c_str(),
+        fsBuilder->appendTextureLookup(&noiseCode, args.fTexSamplers[1], latticeCoords.c_str(),
             kVec2f_GrSLType);
         noiseCode.appendf(".bgra;\n\t%s.y = ", uv);
         noiseCode.appendf(dotLattice, lattice, lattice, inc8bit, fractVal);
@@ -883,7 +883,7 @@
         SkString latticeCoords("");
         latticeCoords.appendf("vec2(%s.w, %s)", bcoords, chanCoord);
         noiseCode.append("\n\tlattice = ");
-        fsBuilder->appendTextureLookup(&noiseCode, args.fSamplers[1], latticeCoords.c_str(),
+        fsBuilder->appendTextureLookup(&noiseCode, args.fTexSamplers[1], latticeCoords.c_str(),
             kVec2f_GrSLType);
         noiseCode.appendf(".bgra;\n\t%s.y = ", uv);
         noiseCode.appendf(dotLattice, lattice, lattice, inc8bit, fractVal);
@@ -895,7 +895,7 @@
         SkString latticeCoords("");
         latticeCoords.appendf("vec2(%s.z, %s)", bcoords, chanCoord);
         noiseCode.append("\n\tlattice = ");
-        fsBuilder->appendTextureLookup(&noiseCode, args.fSamplers[1], latticeCoords.c_str(),
+        fsBuilder->appendTextureLookup(&noiseCode, args.fTexSamplers[1], latticeCoords.c_str(),
             kVec2f_GrSLType);
         noiseCode.appendf(".bgra;\n\t%s.x = ", uv);
         noiseCode.appendf(dotLattice, lattice, lattice, inc8bit, fractVal);
@@ -1175,7 +1175,7 @@
     SkString permCode("return ");
     // FIXME even though I'm creating these textures with kRepeat_TileMode, they're clamped. Not 
     // sure why. Using fract() (here and the next texture lookup) as a workaround.
-    fsBuilder->appendTextureLookup(&permCode, args.fSamplers[0], "vec2(fract(x / 256.0), 0.0)", 
+    fsBuilder->appendTextureLookup(&permCode, args.fTexSamplers[0], "vec2(fract(x / 256.0), 0.0)",
                                    kVec2f_GrSLType);
     permCode.append(".r * 255.0;");
     fsBuilder->emitFunction(kFloat_GrSLType, "perm", SK_ARRAY_COUNT(permArgs), permArgs, 
@@ -1188,7 +1188,7 @@
     };
     SkString gradFuncName;
     SkString gradCode("return dot(");
-    fsBuilder->appendTextureLookup(&gradCode, args.fSamplers[1], "vec2(fract(x / 16.0), 0.0)", 
+    fsBuilder->appendTextureLookup(&gradCode, args.fTexSamplers[1], "vec2(fract(x / 16.0), 0.0)",
                                    kVec2f_GrSLType);
     gradCode.append(".rgb * 255.0 - vec3(1.0), p);");
     fsBuilder->emitFunction(kFloat_GrSLType, "grad", SK_ARRAY_COUNT(gradArgs), gradArgs,