Add addFragPosUniform to GrGLrogramBuilder

src/gpu/gl/builders/GrGLFragmentShaderBuilder.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrGLFragmentShaderBuilder.h"
 #include "GrRenderTarget.h"
 #include "GrGLProgramBuilder.h"
@@ skipping 125 matching lines @@
                                     "gl_FragCoord",
                                     kDefault_GrSLPrecision,
                                     GrGLSLShaderVar::kUpperLeft_Origin);
             fSetupFragPosition = true;
         }
         return "gl_FragCoord";
     } else {
         static const char* kTempName = "tmpXYFragCoord";
         static const char* kCoordName = "fragCoordYDown";
         if (!fSetupFragPosition) {
-            // temporarily change the stage index because we're inserting non-stage code.
-            GrGLProgramBuilder::AutoStageRestore asr(fProgramBuilder);
             SkASSERT(!fProgramBuilder->fUniformHandles.fRTHeightUni.isValid());
             const char* rtHeightName;
 
             fProgramBuilder->fUniformHandles.fRTHeightUni =
-                    fProgramBuilder->addUniform(GrGLProgramBuilder::kFragment_Visibility,
-                                                kFloat_GrSLType,
-                                                kDefault_GrSLPrecision,
-                                                "RTHeight",
-                                                &rtHeightName);
+                    fProgramBuilder->addFragPosUniform(GrGLProgramBuilder::kFragment_Visibility,
+                                                       kFloat_GrSLType,
+                                                       kDefault_GrSLPrecision,
+                                                       "RTHeight",
+                                                       &rtHeightName);
 
             // The Adreno compiler seems to be very touchy about access to "gl_FragCoord".
             // Accessing glFragCoord.zw can cause a program to fail to link. Additionally,
             // depending on the surrounding code, accessing .xy with a uniform involved can
             // do the same thing. Copying gl_FragCoord.xy into a temp vec2 beforehand 
             // (and only accessing .xy) seems to "fix" things.
             this->codePrependf("\tvec4 %s = vec4(%s.x, %s - %s.y, 1.0, 1.0);\n",
                                kCoordName, kTempName, rtHeightName, kTempName);
             this->codePrependf("vec2 %s = gl_FragCoord.xy;", kTempName);
             fSetupFragPosition = true;
@@ skipping 112 matching lines @@
     fMangleString.appendf("_c%d", fSubstageIndices[fSubstageIndices.count() - 2]);
 }
 
 void GrGLFragmentBuilder::onAfterChildProcEmitCode() {
     SkASSERT(fSubstageIndices.count() >= 2);
     fSubstageIndices.pop_back();
     fSubstageIndices.back()++;
     int removeAt = fMangleString.findLastOf('_');
     fMangleString.remove(removeAt, fMangleString.size() - removeAt);
 }