Add function for logging blend info on XP.

src/gpu/gl/GrGLGpu.h

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrGLGpu_DEFINED
 #define GrGLGpu_DEFINED
 
@@ skipping 428 matching lines @@
 
     struct {
         GrBlendEquation fEquation;
         GrBlendCoeff    fSrcCoeff;
         GrBlendCoeff    fDstCoeff;
         GrColor         fConstColor;
         bool            fConstColorValid;
         TriState        fEnabled;
 
         void invalidate() {
-            fEquation = kInvalid_GrBlendEquation;
-            fSrcCoeff = kInvalid_GrBlendCoeff;
-            fDstCoeff = kInvalid_GrBlendCoeff;
+            fEquation = static_cast<GrBlendEquation>(-1);
+            fSrcCoeff = static_cast<GrBlendCoeff>(-1);
+            fDstCoeff = static_cast<GrBlendCoeff>(-1);
             fConstColorValid = false;
             fEnabled = kUnknown_TriState;
         }
     } fHWBlendState;
 
     TriState fMSAAEnabled;
 
     GrStencilSettings           fHWStencilSettings;
     TriState                    fHWStencilTestEnabled;
 
 
     GrPipelineBuilder::DrawFace fHWDrawFace;
     TriState                    fHWWriteToColor;
     TriState                    fHWDitherEnabled;
     uint32_t                    fHWBoundRenderTargetUniqueID;
     SkTArray<uint32_t, true>    fHWBoundTextureUniqueIDs;
 
     ///@}
 
     // we record what stencil format worked last time to hopefully exit early
     // from our loop that tries stencil formats and calls check fb status.
     int fLastSuccessfulStencilFmtIdx;
 
     typedef GrGpu INHERITED;
     friend class GrGLPathRendering; // For accessing setTextureUnit.
 };
 
 #endif