Fix for MSAN unintialized value

src/gpu/effects/GrTextureDomain.h

Index: src/gpu/effects/GrTextureDomain.h
diff --git a/src/gpu/effects/GrTextureDomain.h b/src/gpu/effects/GrTextureDomain.h
index a2e6652e91cf91823cbe167104e4c9f62ab0bbad..11760fb62b5929433acf49226105f8f883e906a7 100644
--- a/src/gpu/effects/GrTextureDomain.h
+++ b/src/gpu/effects/GrTextureDomain.h
@@ -95,7 +95,9 @@ public:
     class GLDomain {
     public:
         GLDomain() {
-            fPrevDomain[0] = SK_FloatNaN;
+            for (int i = 0; i < kPrevDomainCount; i++) {
+                fPrevDomain[i] = SK_FloatNaN;
+            }
             SkDEBUGCODE(fMode = (Mode) -1;)
         }
 
@@ -137,10 +139,11 @@ public:
         }
 
     private:
+        static const int kPrevDomainCount = 4;
         SkDEBUGCODE(Mode                      fMode;)
         GrGLProgramDataManager::UniformHandle fDomainUni;
         SkString                              fDomainName;
-        GrGLfloat                             fPrevDomain[4];
+        GrGLfloat                             fPrevDomain[kPrevDomainCount];
     };
 
 protected: