Use high precision vertex attributes.

src/gpu/gl/GrGLPrimitiveProcessor.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 "GrGLPrimitiveProcessor.h"
 
 #include "builders/GrGLProgramBuilder.h"
@@ skipping 29 matching lines @@
     *colorUniform = pb->addUniform(GrGLProgramBuilder::kFragment_Visibility,
                                    kVec4f_GrSLType,
                                    kDefault_GrSLPrecision,
                                    "Color",
                                    &stagedLocalVarName);
     fs->codeAppendf("%s = %s;", outputName, stagedLocalVarName);
 }
 
 void GrGLPrimitiveProcessor::addUniformViewMatrix(GrGLGPBuilder* pb) {
     fViewMatrixUniform = pb->addUniform(GrGLProgramBuilder::kVertex_Visibility,
-                                        kMat33f_GrSLType, kDefault_GrSLPrecision,
+                                        kMat33f_GrSLType, kHigh_GrSLPrecision,
                                         "uViewM",
                                         &fViewMatrixName);
 }
 
 void GrGLPrimitiveProcessor::setUniformViewMatrix(const GrGLProgramDataManager& pdman,
                                                   const SkMatrix& viewMatrix) {
     if (!viewMatrix.isIdentity() && !fViewMatrix.cheapEqualTo(viewMatrix)) {
         SkASSERT(fViewMatrixUniform.isValid());
         fViewMatrix = viewMatrix;
 
         GrGLfloat viewMatrix[3 * 3];
         GrGLGetMatrix<3>(viewMatrix, fViewMatrix);
         pdman.setMatrix3f(fViewMatrixUniform, viewMatrix);
     }
 }