clean up default precision handling

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 "GrGLShaderStringBuilder.h"
 #include "GrGLProgramBuilder.h"
 #include "../GrGpuGL.h"
 
 #define GL_CALL(X) GR_GL_CALL(fProgramBuilder->gpu()->glInterface(), X)
 #define GL_CALL_RET(R, X) GR_GL_CALL_RET(fProgramBuilder->gpu()->glInterface(), R, X)
 
-// ES2 FS only guarantees mediump and lowp support
-static const GrGLShaderVar::Precision kDefaultFragmentPrecision = GrGLShaderVar::kMedium_Precision;
 const char* GrGLFragmentShaderBuilder::kDstCopyColorName = "_dstColor";
 static const char* declared_color_output_name() { return "fsColorOut"; }
 static const char* dual_source_output_name() { return "dualSourceOut"; }
 static void append_default_precision_qualifier(GrGLShaderVar::Precision p,
                                                GrGLStandard standard,
                                                SkString* str) {
     // Desktop GLSL has added precision qualifiers but they don't do anything.
     if (kGLES_GrGLStandard == standard) {
         switch (p) {
             case GrGLShaderVar::kHigh_Precision:
                 str->append("precision highp float;\n");
                 break;
             case GrGLShaderVar::kMedium_Precision:
                 str->append("precision mediump float;\n");
                 break;
             case GrGLShaderVar::kLow_Precision:
                 str->append("precision lowp float;\n");
                 break;
-            case GrGLShaderVar::kDefault_Precision:
-                SkFAIL("Default precision now allowed.");
             default:
                 SkFAIL("Unknown precision value.");
         }
     }
 }
 
 GrGLFragmentShaderBuilder::DstReadKey
 GrGLFragmentShaderBuilder::KeyForDstRead(const GrTexture* dstCopy, const GrGLCaps& caps) {
     uint32_t key = kYesDstRead_DstReadKeyBit;
     if (caps.fbFetchSupport()) {
@@ skipping 255 matching lines @@
     }
 
     this->codeAppendf("\t%s = %s;\n", this->getPrimaryColorOutputName(), fragColor.c_str());
 }
 
 bool GrGLFragmentShaderBuilder::compileAndAttachShaders(GrGLuint programId,
                                                         SkTDArray<GrGLuint>* shaderIds) const {
     GrGpuGL* gpu = fProgramBuilder->gpu();
     SkString fragShaderSrc(GrGetGLSLVersionDecl(gpu->ctxInfo()));
     fragShaderSrc.append(fExtensions);
-    append_default_precision_qualifier(kDefaultFragmentPrecision,
+    append_default_precision_qualifier(GrShaderVar::kDefault_Precision,
                                        gpu->glStandard(),
                                        &fragShaderSrc);
     fProgramBuilder->appendUniformDecls(GrGLProgramBuilder::kFragment_Visibility, &fragShaderSrc);
     this->appendDecls(fInputs, &fragShaderSrc);
     // We shouldn't have declared outputs on 1.10
     SkASSERT(k110_GrGLSLGeneration != gpu->glslGeneration() || fOutputs.empty());
     this->appendDecls(fOutputs, &fragShaderSrc);
     fragShaderSrc.append(fFunctions);
     fragShaderSrc.append("void main() {\n");
     fragShaderSrc.append(fCode);
@@ skipping 22 matching lines @@
     }
 }
 
 void GrGLFragmentShaderBuilder::addVarying(GrGLVarying* v, GrGLShaderVar::Precision fsPrec) {
     v->fFsIn = v->fVsOut;
     if (v->fGsOut) {
         v->fFsIn = v->fGsOut;
     }
     fInputs.push_back().set(v->fType, GrGLShaderVar::kVaryingIn_TypeModifier, v->fFsIn, fsPrec);
 }