Fix a division by zero when multiplying 0 * y with SafeNumerics.

base/numerics/safe_numerics_unittest.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #if defined(COMPILER_MSVC) && defined(ARCH_CPU_32_BITS)
 #include <mmintrin.h>
 #endif
 #include <stdint.h>
 
 #include <limits>
@@ skipping 221 matching lines @@
   TEST_EXPECTED_VALUE(-1, (CheckedNumeric<Dst>() - 1));
   TEST_EXPECTED_VALUE(0, (CheckedNumeric<Dst>(1) - 1));
   TEST_EXPECTED_VALUE(-2, (CheckedNumeric<Dst>(-1) - 1));
   TEST_EXPECTED_VALIDITY(RANGE_VALID,
                          CheckedNumeric<Dst>(DstLimits::max()) - 1);
 
   // Generic multiplication.
   TEST_EXPECTED_VALUE(0, (CheckedNumeric<Dst>() * 1));
   TEST_EXPECTED_VALUE(1, (CheckedNumeric<Dst>(1) * 1));
   TEST_EXPECTED_VALUE(-2, (CheckedNumeric<Dst>(-1) * 2));
+  TEST_EXPECTED_VALUE(0, (CheckedNumeric<Dst>(0) * 0));
+  TEST_EXPECTED_VALUE(0, (CheckedNumeric<Dst>(-1) * 0));
+  TEST_EXPECTED_VALUE(0, (CheckedNumeric<Dst>(0) * -1));
   TEST_EXPECTED_VALIDITY(
       RANGE_OVERFLOW, CheckedNumeric<Dst>(DstLimits::max()) * DstLimits::max());
 
   // Generic division.
   TEST_EXPECTED_VALUE(0, CheckedNumeric<Dst>() / 1);
   TEST_EXPECTED_VALUE(1, CheckedNumeric<Dst>(1) / 1);
   TEST_EXPECTED_VALUE(DstLimits::min() / 2,
                       CheckedNumeric<Dst>(DstLimits::min()) / 2);
   TEST_EXPECTED_VALUE(DstLimits::max() / 2,
                       CheckedNumeric<Dst>(DstLimits::max()) / 2);
@@ skipping 315 matching lines @@
             static_cast<int>(small_positive));
   EXPECT_EQ(saturated_cast<unsigned>(small_negative),
             static_cast<unsigned>(0));
   EXPECT_EQ(saturated_cast<int>(double_small),
             static_cast<int>(double_small));
   EXPECT_EQ(saturated_cast<int>(double_large), numeric_limits<int>::max());
   EXPECT_EQ(saturated_cast<float>(double_large), double_infinity);
   EXPECT_EQ(saturated_cast<float>(-double_large), -double_infinity);
 }