Force input coverage to be only a byte in gpu shaders.

src/gpu/GrAAHairLinePathRenderer.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrAAHairLinePathRenderer.h"
 
 #include "GrContext.h"
@@ skipping 632 matching lines @@
 
 // position + edge
 extern const GrVertexAttrib gHairlineBezierAttribs[] = {
     {kVec2f_GrVertexAttribType, 0,                  kPosition_GrVertexAttribBinding},
     {kVec4f_GrVertexAttribType, sizeof(SkPoint),    kGeometryProcessor_GrVertexAttribBinding}
 };
 
 // position + coverage
 extern const GrVertexAttrib gHairlineLineAttribs[] = {
     {kVec2f_GrVertexAttribType,  0,               kPosition_GrVertexAttribBinding},
-    {kVec4ub_GrVertexAttribType, sizeof(SkPoint), kCoverage_GrVertexAttribBinding},
+    {kUByte_GrVertexAttribType, sizeof(SkPoint), kCoverage_GrVertexAttribBinding},
 };
 
 };
 
 bool GrAAHairLinePathRenderer::createLineGeom(const SkPath& path,
                                               GrDrawTarget* target,
                                               const PtArray& lines,
                                               int lineCnt,
                                               GrDrawTarget::AutoReleaseGeometry* arg,
                                               SkRect* devBounds) {
@@ skipping 303 matching lines @@
                                     &devBounds);
                 conics += n;
             }
         }
     }
 
     target->resetIndexSource();
 
     return true;
 }