Add sk_careful_memcpy to catch undefined behavior in memcpy.

src/core/SkPathRef.cpp

Index: src/core/SkPathRef.cpp
diff --git a/src/core/SkPathRef.cpp b/src/core/SkPathRef.cpp
index 12429aecfcc889b3244ab03c40dbfea423464780..14e6b0c658601f67dfbffacadc79cc9f538b1189 100644
--- a/src/core/SkPathRef.cpp
+++ b/src/core/SkPathRef.cpp
@@ -72,7 +72,9 @@ void SkPathRef::CreateTransformedCopy(SkAutoTUnref<SkPathRef>* dst,
 
     if (*dst != &src) {
         (*dst)->resetToSize(src.fVerbCnt, src.fPointCnt, src.fConicWeights.count());
-        memcpy((*dst)->verbsMemWritable(), src.verbsMemBegin(), src.fVerbCnt * sizeof(uint8_t));
+        if (src.verbsMemBegin()) {
+            memcpy((*dst)->verbsMemWritable(), src.verbsMemBegin(), src.fVerbCnt * sizeof(uint8_t));
+        }
         (*dst)->fConicWeights = src.fConicWeights;
     }
 
@@ -275,8 +277,12 @@ void SkPathRef::copy(const SkPathRef& ref,
     SkDEBUGCODE(this->validate();)
     this->resetToSize(ref.fVerbCnt, ref.fPointCnt, ref.fConicWeights.count(),
                         additionalReserveVerbs, additionalReservePoints);
-    memcpy(this->verbsMemWritable(), ref.verbsMemBegin(), ref.fVerbCnt * sizeof(uint8_t));
-    memcpy(this->fPoints, ref.fPoints, ref.fPointCnt * sizeof(SkPoint));
+    if (ref.verbsMemBegin()) {
+        memcpy(this->verbsMemWritable(), ref.verbsMemBegin(), ref.fVerbCnt * sizeof(uint8_t));
+    }
+    if (ref.fPoints) {
+        memcpy(this->fPoints, ref.fPoints, ref.fPointCnt * sizeof(SkPoint));
+    }
     fConicWeights = ref.fConicWeights;
     fBoundsIsDirty = ref.fBoundsIsDirty;
     if (!fBoundsIsDirty) {