one channel texture fix for blur shader

src/effects/SkBlurMaskFilter.cpp

 
 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBlurMaskFilter.h"
 #include "SkBlurMask.h"
@@ skipping 616 matching lines @@
 void OutputRectBlurProfileLookup(GrGLShaderBuilder* builder,
                                  const GrGLShaderBuilder::TextureSampler& sampler,
                                  const char *output,
                                  const char *profileSize, const char *loc,
                                  const char *blurred_width,
                                  const char *sharp_width) {
     builder->fsCodeAppendf("\t\tfloat coord = (0.5 * (abs(2*%s - %s) - %s))/%s;\n",
                            loc, blurred_width, sharp_width, profileSize);
     builder->fsCodeAppendf("\t\t%s = ", output);
     builder->fsAppendTextureLookup(sampler, "vec2(coord,0.5)");
-    builder->fsCodeAppend(";\n");
+    builder->fsCodeAppend(".a;\n");
 }
 
 void GrGLRectBlurEffect::emitCode(GrGLShaderBuilder* builder,
                                  const GrDrawEffect&,
                                  EffectKey key,
                                  const char* outputColor,
                                  const char* inputColor,
                                  const TransformedCoordsArray& coords,
                                  const TextureSamplerArray& samplers) {
 
@@ skipping 564 matching lines @@
     } else {
         str->append("None");
     }
     str->append("))");
 }
 #endif
 
 SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_START(SkBlurMaskFilter)
     SK_DEFINE_FLATTENABLE_REGISTRAR_ENTRY(SkBlurMaskFilterImpl)
 SK_DEFINE_FLATTENABLE_REGISTRAR_GROUP_END