clean up default precision handling

src/gpu/gl/builders/GrGLProgramBuilder.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 "GrGLProgramBuilder.h"
 #include "gl/GrGLProgram.h"
 #include "gl/GrGLSLPrettyPrint.h"
 #include "gl/GrGLUniformHandle.h"
 #include "../GrGpuGL.h"
 #include "GrCoordTransform.h"
 #include "GrGLLegacyNvprProgramBuilder.h"
 #include "GrGLNvprProgramBuilder.h"
 #include "GrGLProgramBuilder.h"
 #include "GrTexture.h"
 #include "SkRTConf.h"
 #include "SkTraceEvent.h"
 
 #define GL_CALL(X) GR_GL_CALL(this->gpu()->glInterface(), X)
 #define GL_CALL_RET(R, X) GR_GL_CALL_RET(this->gpu()->glInterface(), R, X)
 
-// ES2 FS only guarantees mediump and lowp support
-static const GrGLShaderVar::Precision kDefaultFragmentPrecision = GrGLShaderVar::kMedium_Precision;
-
 //////////////////////////////////////////////////////////////////////////////
 
 const int GrGLProgramBuilder::kVarsPerBlock = 8;
 
 GrGLProgram* GrGLProgramBuilder::CreateProgram(const GrOptDrawState& optState,
                                                GrGpu::DrawType drawType,
                                                GrGpuGL* gpu) {
     // create a builder.  This will be handed off to effects so they can use it to add
     // uniforms, varyings, textures, etc
     SkAutoTDelete<GrGLProgramBuilder> builder(CreateProgramBuilder(optState,
@@ skipping 135 matching lines @@
     }
     this->nameVariable(uni.fVariable.accessName(), prefix, name);
     uni.fVariable.setArrayCount(count);
     uni.fVisibility = visibility;
 
     // If it is visible in both the VS and FS, the precision must match.
     // We declare a default FS precision, but not a default VS. So set the var
     // to use the default FS precision.
     if ((kVertex_Visibility | kFragment_Visibility) == visibility) {
         // the fragment and vertex precisions must match
-        uni.fVariable.setPrecision(kDefaultFragmentPrecision);
+        uni.fVariable.setPrecision(GrShaderVar::kDefault_Precision);
     }
 
     if (outName) {
         *outName = uni.fVariable.c_str();
     }
     return GrGLProgramDataManager::UniformHandle::CreateFromUniformIndex(fUniforms.count() - 1);
 }
 
 void GrGLProgramBuilder::appendUniformDecls(ShaderVisibility visibility,
                                             SkString* out) const {
@@ skipping 361 matching lines @@
 }
 
 ///////////////////////////////////////////////////////////////////////////////////////////////////
 
 GrGLInstalledFragProcs::~GrGLInstalledFragProcs() {
     int numProcs = fProcs.count();
     for (int e = 0; e < numProcs; ++e) {
         SkDELETE(fProcs[e]);
     }
 }