Watch out for SkFixed overflow in SkMipMap.cpp.

Tested with -fsanitize=signed-integer-overflow.
This new assert used to trigger in MipMap unit test.

Don't appear to be any GM diffs.

BUG=skia:

Review URL: https://codereview.chromium.org/729373004

1 files changed, 1 insertions, 0 deletions

diff --git a/include/core/SkTypes.h b/include/core/SkTypes.h
index 0e9e230349..a38be84d8f 100644
--- a/include/core/SkTypes.h
+++ b/include/core/SkTypes.h
@@ -352,6 +352,7 @@ template <typename T> inline void SkTSwap(T& a, T& b) {
 }
 
 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;
     }