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

src/gpu/gl/GrGLVertexArray.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrGLVertexArray_DEFINED
 #define GrGLVertexArray_DEFINED
 
@@ skipping 14 matching lines @@
     GrGLboolean fNormalized;
 };
 
 static inline const GrGLAttribLayout& GrGLAttribTypeToLayout(GrVertexAttribType type) {
     SkASSERT(type >= 0 && type < kGrVertexAttribTypeCount);
     static const GrGLAttribLayout kLayouts[kGrVertexAttribTypeCount] = {
         {1, GR_GL_FLOAT, false},         // kFloat_GrVertexAttribType
         {2, GR_GL_FLOAT, false},         // kVec2f_GrVertexAttribType
         {3, GR_GL_FLOAT, false},         // kVec3f_GrVertexAttribType
         {4, GR_GL_FLOAT, false},         // kVec4f_GrVertexAttribType
+        {1, GR_GL_UNSIGNED_BYTE, true},  // kUByte_GrVertexAttribType
         {4, GR_GL_UNSIGNED_BYTE, true},  // kVec4ub_GrVertexAttribType
     };
     GR_STATIC_ASSERT(0 == kFloat_GrVertexAttribType);
     GR_STATIC_ASSERT(1 == kVec2f_GrVertexAttribType);
     GR_STATIC_ASSERT(2 == kVec3f_GrVertexAttribType);
     GR_STATIC_ASSERT(3 == kVec4f_GrVertexAttribType);
-    GR_STATIC_ASSERT(4 == kVec4ub_GrVertexAttribType);
+    GR_STATIC_ASSERT(4 == kUByte_GrVertexAttribType);
+    GR_STATIC_ASSERT(5 == kVec4ub_GrVertexAttribType);
     GR_STATIC_ASSERT(SK_ARRAY_COUNT(kLayouts) == kGrVertexAttribTypeCount);
     return kLayouts[type];
 }
 
 /**
  * This sets and tracks the vertex attribute array state. It is used internally by GrGLVertexArray
  * (below) but is separate because it is also used to track the state of vertex array object 0.
  */
 class GrGLAttribArrayState {
 public:
@@ skipping 115 matching lines @@
 private:
     GrGLuint                fID;
     GrGLAttribArrayState    fAttribArrays;
     GrGLuint                fIndexBufferID;
     bool                    fIndexBufferIDIsValid;
 
     typedef GrGpuResource INHERITED;
 };
 
 #endif