fix build error in chromium

src/gpu/effects/GrDistanceFieldTextureEffect.cpp

Index: src/gpu/effects/GrDistanceFieldTextureEffect.cpp
diff --git a/src/gpu/effects/GrDistanceFieldTextureEffect.cpp b/src/gpu/effects/GrDistanceFieldTextureEffect.cpp
index 2998a5473358333f737af6680b31e0a874048713..9159a701e32a966bbb0ba1a3d465b35cd3abc6d2 100755
--- a/src/gpu/effects/GrDistanceFieldTextureEffect.cpp
+++ b/src/gpu/effects/GrDistanceFieldTextureEffect.cpp
@@ -56,7 +56,7 @@ public:
                                        fsCoordName.c_str(),
                                        kVec2f_GrSLType);
         builder->fsCodeAppend(";\n");
-        builder->fsCodeAppend("\tfloat distance = "MULTIPLIER"*(texColor.r - "THRESHOLD");\n");
+        builder->fsCodeAppend("\tfloat distance = " MULTIPLIER "*(texColor.r - " THRESHOLD ");\n");
 
         // we adjust for the effect of the transformation on the distance by using
         // the length of the gradient of the texture coordinates. We use st coordinates