Add option to add precision to varyings in shader

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 "gl/GrGLProgram.h"
 #include "gl/GrGLSLPrettyPrint.h"
 #include "gl/GrGLUniformHandle.h"
@@ skipping 325 matching lines @@
     fVS.emitCodeBeforeEffects(color, coverage);
 }
 
 void GrGLFullProgramBuilder::emitCodeAfterEffects() {
     fVS.emitCodeAfterEffects();
 }
 
 void GrGLFullProgramBuilder::addVarying(GrSLType type,
                                         const char* name,
                                         const char** vsOutName,
-                                        const char** fsInName) {
+                                        const char** fsInName,
+                                        GrGLShaderVar::Precision fsPrecision) {
     fVS.addVarying(type, name, vsOutName);
 
     SkString* fsInputName = fVS.fOutputs.back().accessName();
 
 #if GR_GL_EXPERIMENTAL_GS
     if (desc().getHeader().fExperimentalGS) {
        // TODO let the caller use these names
        fGS.addVarying(type, fsInputName->c_str(), NULL);
        fsInputName = fGS.fOutputs.back().accessName();
     }
 #endif
-    fFS.addVarying(type, fsInputName->c_str(), fsInName);
+    fFS.addVarying(type, fsInputName->c_str(), fsInName, fsPrecision);
 }
 
 GrGLFullProgramBuilder::VaryingHandle
 GrGLFullProgramBuilder::addSeparableVarying(GrSLType type,
                                             const char* name,
                                             const char** vsOutName,
                                             const char** fsInName) {
     addVarying(type, name, vsOutName, fsInName);
     SeparableVaryingInfo& varying = fSeparableVaryingInfos.push_back();
     varying.fVariable = fFS.fInputs.back();
@@ skipping 56 matching lines @@
 
     GrGLPathTexGenProgramEffectsBuilder pathTexGenEffectsBuilder(this,
                                                                  effectCnt);
     this->INHERITED::createAndEmitEffects(&pathTexGenEffectsBuilder,
                                           effectStages,
                                           effectCnt,
                                           keyProvider,
                                           inOutFSColor);
     return pathTexGenEffectsBuilder.finish();
 }