Watch out for SkFixed overflow in SkMipMap.cpp.

include/core/SkTypes.h

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkTypes_DEFINED
 #define SkTypes_DEFINED
 
@@ skipping 334 matching lines @@
 
 /** Generic swap function. Classes with efficient swaps should specialize this function to take
     their fast path. This function is used by SkTSort. */
 template <typename T> inline void SkTSwap(T& a, T& b) {
     T c(a);
     a = b;
     b = c;
 }
 
 static inline int32_t SkAbs32(int32_t value) {
+    SkASSERT(value != SK_NaN32);  // The most negative int32_t can't be negated.
     if (value < 0) {
         value = -value;
     }
     return value;
 }
 
 template <typename T> inline T SkTAbs(T value) {
     if (value < 0) {
         value = -value;
     }
@@ skipping 303 matching lines @@
 private:
     void*       fPtr;
     size_t      fSize;  // can be larger than the requested size (see kReuse)
     uint32_t    fStorage[(kSize + 3) >> 2];
 };
 // Can't guard the constructor because it's a template class.
 
 #endif /* C++ */
 
 #endif