Fix case where GrGLEffectMatrix gives back a dangling ptr for the coords var name.

src/effects/gradients/SkSweepGradient.cpp

 
 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkSweepGradient.h"
 
@@ skipping 455 matching lines @@
 
 /////////////////////////////////////////////////////////////////////
 
 void GrGLSweepGradient::emitCode(GrGLShaderBuilder* builder,
                                  const GrDrawEffect&,
                                  EffectKey key,
                                  const char* outputColor,
                                  const char* inputColor,
                                  const TextureSamplerArray& samplers) {
     this->emitYCoordUniform(builder);
-    const char* coords;
+    SkString coords;
     this->setupMatrix(builder, key, &coords);
     SkString t;
-    t.printf("atan(- %s.y, - %s.x) * 0.1591549430918 + 0.5", coords, coords);
+    t.printf("atan(- %s.y, - %s.x) * 0.1591549430918 + 0.5", coords.c_str(), coords.c_str());
     this->emitColorLookup(builder, t.c_str(), outputColor, inputColor, samplers[0]);
 }
 
 /////////////////////////////////////////////////////////////////////
 
 GrEffectRef* SkSweepGradient::asNewEffect(GrContext* context, const SkPaint&) const {
     SkMatrix matrix;
     if (!this->getLocalMatrix().invert(&matrix)) {
         return NULL;
     }
@@ skipping 18 matching lines @@
     str->appendScalar(fCenter.fX);
     str->append(", ");
     str->appendScalar(fCenter.fY);
     str->append(") ");
 
     this->INHERITED::toString(str);
 
     str->append(")");
 }
 #endif