diff --git a/base/safe_compare_unittest.cc b/base/safe_compare_unittest.cc
new file mode 100644
index 0000000..12ab469
--- /dev/null
+++ b/base/safe_compare_unittest.cc
@@ -0,0 +1,379 @@
+/*
+ *  Copyright 2016 The WebRTC Project Authors. All rights reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include <limits>
+
+#include "webrtc/base/safe_compare.h"
+#include "webrtc/test/gtest.h"
+
+namespace rtc {
+
+namespace {
+
+constexpr std::uintmax_t umax = std::numeric_limits<std::uintmax_t>::max();
+constexpr std::intmax_t imin = std::numeric_limits<std::intmax_t>::min();
+constexpr std::intmax_t m1 = -1;
+
+// m1 and umax have the same representation because we use 2's complement
+// arithmetic, so naive casting will confuse them.
+static_assert(static_cast<std::uintmax_t>(m1) == umax, "");
+static_assert(m1 == static_cast<std::intmax_t>(umax), "");
+
+std::pair<int, int> p1(1, 1);
+std::pair<int, int> p2(1, 2);
+
+}  // namespace
+
+// clang-format off
+
+// These functions aren't used in the tests, but it's useful to look at the
+// compiler output for them, and verify that (1) the same-signedness *Safe
+// functions result in exactly the same code as their *Ref counterparts, and
+// that (2) the mixed-signedness *Safe functions have just a few extra
+// arithmetic and logic instructions (but no extra control flow instructions).
+bool TestLessThanRef(      int a,      int b) { return a < b; }
+bool TestLessThanRef( unsigned a, unsigned b) { return a < b; }
+bool TestLessThanSafe(     int a,      int b) { return safe_cmp::Lt(a, b); }
+bool TestLessThanSafe(unsigned a, unsigned b) { return safe_cmp::Lt(a, b); }
+bool TestLessThanSafe(unsigned a,      int b) { return safe_cmp::Lt(a, b); }
+bool TestLessThanSafe(     int a, unsigned b) { return safe_cmp::Lt(a, b); }
+
+// For these, we expect the *Ref and *Safe functions to result in identical
+// code, except for the ones that compare a signed variable with an unsigned
+// constant; in that case, the *Ref function does an unsigned comparison (fast
+// but incorrect) and the *Safe function spends a few extra instructions on
+// doing it right.
+bool TestLessThan17Ref(       int a) { return a < 17; }
+bool TestLessThan17Ref(  unsigned a) { return a < 17; }
+bool TestLessThan17uRef(      int a) { return static_cast<unsigned>(a) < 17u; }
+bool TestLessThan17uRef( unsigned a) { return a < 17u; }
+bool TestLessThan17Safe(      int a) { return safe_cmp::Lt(a, 17); }
+bool TestLessThan17Safe( unsigned a) { return safe_cmp::Lt(a, 17); }
+bool TestLessThan17uSafe(     int a) { return safe_cmp::Lt(a, 17u); }
+bool TestLessThan17uSafe(unsigned a) { return safe_cmp::Lt(a, 17u); }
+
+// Cases where we can't convert to a larger signed type.
+bool TestLessThanMax( intmax_t a, uintmax_t b) { return safe_cmp::Lt(a, b); }
+bool TestLessThanMax(uintmax_t a,  intmax_t b) { return safe_cmp::Lt(a, b); }
+bool TestLessThanMax17u( intmax_t a) { return safe_cmp::Lt(a, uintmax_t{17}); }
+bool TestLessThanMax17( uintmax_t a) { return safe_cmp::Lt(a,  intmax_t{17}); }
+
+// Cases where the compiler should be able to compute the result at compile
+// time.
+bool TestLessThanConst1() { return safe_cmp::Lt(  -1,    1); }
+bool TestLessThanConst2() { return safe_cmp::Lt(  m1, umax); }
+bool TestLessThanConst3() { return safe_cmp::Lt(umax, imin); }
+bool TestLessThanConst4(unsigned a) { return safe_cmp::Lt( a, -1); }
+bool TestLessThanConst5(unsigned a) { return safe_cmp::Lt(-1,  a); }
+bool TestLessThanConst6(unsigned a) { return safe_cmp::Lt( a,  a); }
+
+// clang-format on
+
+TEST(SafeCmpTest, Eq) {
+  EXPECT_FALSE(safe_cmp::Eq(-1, 2));
+  EXPECT_FALSE(safe_cmp::Eq(-1, 2u));
+  EXPECT_FALSE(safe_cmp::Eq(2, -1));
+  EXPECT_FALSE(safe_cmp::Eq(2u, -1));
+
+  EXPECT_FALSE(safe_cmp::Eq(1, 2));
+  EXPECT_FALSE(safe_cmp::Eq(1, 2u));
+  EXPECT_FALSE(safe_cmp::Eq(1u, 2));
+  EXPECT_FALSE(safe_cmp::Eq(1u, 2u));
+  EXPECT_FALSE(safe_cmp::Eq(2, 1));
+  EXPECT_FALSE(safe_cmp::Eq(2, 1u));
+  EXPECT_FALSE(safe_cmp::Eq(2u, 1));
+  EXPECT_FALSE(safe_cmp::Eq(2u, 1u));
+
+  EXPECT_TRUE(safe_cmp::Eq(2, 2));
+  EXPECT_TRUE(safe_cmp::Eq(2, 2u));
+  EXPECT_TRUE(safe_cmp::Eq(2u, 2));
+  EXPECT_TRUE(safe_cmp::Eq(2u, 2u));
+
+  EXPECT_TRUE(safe_cmp::Eq(imin, imin));
+  EXPECT_FALSE(safe_cmp::Eq(imin, umax));
+  EXPECT_FALSE(safe_cmp::Eq(umax, imin));
+  EXPECT_TRUE(safe_cmp::Eq(umax, umax));
+
+  EXPECT_TRUE(safe_cmp::Eq(m1, m1));
+  EXPECT_FALSE(safe_cmp::Eq(m1, umax));
+  EXPECT_FALSE(safe_cmp::Eq(umax, m1));
+  EXPECT_TRUE(safe_cmp::Eq(umax, umax));
+
+  EXPECT_FALSE(safe_cmp::Eq(1, 2));
+  EXPECT_FALSE(safe_cmp::Eq(1, 2.0));
+  EXPECT_FALSE(safe_cmp::Eq(1.0, 2));
+  EXPECT_FALSE(safe_cmp::Eq(1.0, 2.0));
+  EXPECT_FALSE(safe_cmp::Eq(2, 1));
+  EXPECT_FALSE(safe_cmp::Eq(2, 1.0));
+  EXPECT_FALSE(safe_cmp::Eq(2.0, 1));
+  EXPECT_FALSE(safe_cmp::Eq(2.0, 1.0));
+
+  EXPECT_TRUE(safe_cmp::Eq(2, 2));
+  EXPECT_TRUE(safe_cmp::Eq(2, 2.0));
+  EXPECT_TRUE(safe_cmp::Eq(2.0, 2));
+  EXPECT_TRUE(safe_cmp::Eq(2.0, 2.0));
+
+  EXPECT_TRUE(safe_cmp::Eq(p1, p1));
+  EXPECT_FALSE(safe_cmp::Eq(p1, p2));
+  EXPECT_FALSE(safe_cmp::Eq(p2, p1));
+  EXPECT_TRUE(safe_cmp::Eq(p2, p2));
+}
+
+TEST(SafeCmpTest, Ne) {
+  EXPECT_TRUE(safe_cmp::Ne(-1, 2));
+  EXPECT_TRUE(safe_cmp::Ne(-1, 2u));
+  EXPECT_TRUE(safe_cmp::Ne(2, -1));
+  EXPECT_TRUE(safe_cmp::Ne(2u, -1));
+
+  EXPECT_TRUE(safe_cmp::Ne(1, 2));
+  EXPECT_TRUE(safe_cmp::Ne(1, 2u));
+  EXPECT_TRUE(safe_cmp::Ne(1u, 2));
+  EXPECT_TRUE(safe_cmp::Ne(1u, 2u));
+  EXPECT_TRUE(safe_cmp::Ne(2, 1));
+  EXPECT_TRUE(safe_cmp::Ne(2, 1u));
+  EXPECT_TRUE(safe_cmp::Ne(2u, 1));
+  EXPECT_TRUE(safe_cmp::Ne(2u, 1u));
+
+  EXPECT_FALSE(safe_cmp::Ne(2, 2));
+  EXPECT_FALSE(safe_cmp::Ne(2, 2u));
+  EXPECT_FALSE(safe_cmp::Ne(2u, 2));
+  EXPECT_FALSE(safe_cmp::Ne(2u, 2u));
+
+  EXPECT_FALSE(safe_cmp::Ne(imin, imin));
+  EXPECT_TRUE(safe_cmp::Ne(imin, umax));
+  EXPECT_TRUE(safe_cmp::Ne(umax, imin));
+  EXPECT_FALSE(safe_cmp::Ne(umax, umax));
+
+  EXPECT_FALSE(safe_cmp::Ne(m1, m1));
+  EXPECT_TRUE(safe_cmp::Ne(m1, umax));
+  EXPECT_TRUE(safe_cmp::Ne(umax, m1));
+  EXPECT_FALSE(safe_cmp::Ne(umax, umax));
+
+  EXPECT_TRUE(safe_cmp::Ne(1, 2));
+  EXPECT_TRUE(safe_cmp::Ne(1, 2.0));
+  EXPECT_TRUE(safe_cmp::Ne(1.0, 2));
+  EXPECT_TRUE(safe_cmp::Ne(1.0, 2.0));
+  EXPECT_TRUE(safe_cmp::Ne(2, 1));
+  EXPECT_TRUE(safe_cmp::Ne(2, 1.0));
+  EXPECT_TRUE(safe_cmp::Ne(2.0, 1));
+  EXPECT_TRUE(safe_cmp::Ne(2.0, 1.0));
+
+  EXPECT_FALSE(safe_cmp::Ne(2, 2));
+  EXPECT_FALSE(safe_cmp::Ne(2, 2.0));
+  EXPECT_FALSE(safe_cmp::Ne(2.0, 2));
+  EXPECT_FALSE(safe_cmp::Ne(2.0, 2.0));
+
+  EXPECT_FALSE(safe_cmp::Ne(p1, p1));
+  EXPECT_TRUE(safe_cmp::Ne(p1, p2));
+  EXPECT_TRUE(safe_cmp::Ne(p2, p1));
+  EXPECT_FALSE(safe_cmp::Ne(p2, p2));
+}
+
+TEST(SafeCmpTest, Lt) {
+  EXPECT_TRUE(safe_cmp::Lt(-1, 2));
+  EXPECT_TRUE(safe_cmp::Lt(-1, 2u));
+  EXPECT_FALSE(safe_cmp::Lt(2, -1));
+  EXPECT_FALSE(safe_cmp::Lt(2u, -1));
+
+  EXPECT_TRUE(safe_cmp::Lt(1, 2));
+  EXPECT_TRUE(safe_cmp::Lt(1, 2u));
+  EXPECT_TRUE(safe_cmp::Lt(1u, 2));
+  EXPECT_TRUE(safe_cmp::Lt(1u, 2u));
+  EXPECT_FALSE(safe_cmp::Lt(2, 1));
+  EXPECT_FALSE(safe_cmp::Lt(2, 1u));
+  EXPECT_FALSE(safe_cmp::Lt(2u, 1));
+  EXPECT_FALSE(safe_cmp::Lt(2u, 1u));
+
+  EXPECT_FALSE(safe_cmp::Lt(2, 2));
+  EXPECT_FALSE(safe_cmp::Lt(2, 2u));
+  EXPECT_FALSE(safe_cmp::Lt(2u, 2));
+  EXPECT_FALSE(safe_cmp::Lt(2u, 2u));
+
+  EXPECT_FALSE(safe_cmp::Lt(imin, imin));
+  EXPECT_TRUE(safe_cmp::Lt(imin, umax));
+  EXPECT_FALSE(safe_cmp::Lt(umax, imin));
+  EXPECT_FALSE(safe_cmp::Lt(umax, umax));
+
+  EXPECT_FALSE(safe_cmp::Lt(m1, m1));
+  EXPECT_TRUE(safe_cmp::Lt(m1, umax));
+  EXPECT_FALSE(safe_cmp::Lt(umax, m1));
+  EXPECT_FALSE(safe_cmp::Lt(umax, umax));
+
+  EXPECT_TRUE(safe_cmp::Lt(1, 2));
+  EXPECT_TRUE(safe_cmp::Lt(1, 2.0));
+  EXPECT_TRUE(safe_cmp::Lt(1.0, 2));
+  EXPECT_TRUE(safe_cmp::Lt(1.0, 2.0));
+  EXPECT_FALSE(safe_cmp::Lt(2, 1));
+  EXPECT_FALSE(safe_cmp::Lt(2, 1.0));
+  EXPECT_FALSE(safe_cmp::Lt(2.0, 1));
+  EXPECT_FALSE(safe_cmp::Lt(2.0, 1.0));
+
+  EXPECT_FALSE(safe_cmp::Lt(2, 2));
+  EXPECT_FALSE(safe_cmp::Lt(2, 2.0));
+  EXPECT_FALSE(safe_cmp::Lt(2.0, 2));
+  EXPECT_FALSE(safe_cmp::Lt(2.0, 2.0));
+
+  EXPECT_FALSE(safe_cmp::Lt(p1, p1));
+  EXPECT_TRUE(safe_cmp::Lt(p1, p2));
+  EXPECT_FALSE(safe_cmp::Lt(p2, p1));
+  EXPECT_FALSE(safe_cmp::Lt(p2, p2));
+}
+
+TEST(SafeCmpTest, Le) {
+  EXPECT_TRUE(safe_cmp::Le(-1, 2));
+  EXPECT_TRUE(safe_cmp::Le(-1, 2u));
+  EXPECT_FALSE(safe_cmp::Le(2, -1));
+  EXPECT_FALSE(safe_cmp::Le(2u, -1));
+
+  EXPECT_TRUE(safe_cmp::Le(1, 2));
+  EXPECT_TRUE(safe_cmp::Le(1, 2u));
+  EXPECT_TRUE(safe_cmp::Le(1u, 2));
+  EXPECT_TRUE(safe_cmp::Le(1u, 2u));
+  EXPECT_FALSE(safe_cmp::Le(2, 1));
+  EXPECT_FALSE(safe_cmp::Le(2, 1u));
+  EXPECT_FALSE(safe_cmp::Le(2u, 1));
+  EXPECT_FALSE(safe_cmp::Le(2u, 1u));
+
+  EXPECT_TRUE(safe_cmp::Le(2, 2));
+  EXPECT_TRUE(safe_cmp::Le(2, 2u));
+  EXPECT_TRUE(safe_cmp::Le(2u, 2));
+  EXPECT_TRUE(safe_cmp::Le(2u, 2u));
+
+  EXPECT_TRUE(safe_cmp::Le(imin, imin));
+  EXPECT_TRUE(safe_cmp::Le(imin, umax));
+  EXPECT_FALSE(safe_cmp::Le(umax, imin));
+  EXPECT_TRUE(safe_cmp::Le(umax, umax));
+
+  EXPECT_TRUE(safe_cmp::Le(m1, m1));
+  EXPECT_TRUE(safe_cmp::Le(m1, umax));
+  EXPECT_FALSE(safe_cmp::Le(umax, m1));
+  EXPECT_TRUE(safe_cmp::Le(umax, umax));
+
+  EXPECT_TRUE(safe_cmp::Le(1, 2));
+  EXPECT_TRUE(safe_cmp::Le(1, 2.0));
+  EXPECT_TRUE(safe_cmp::Le(1.0, 2));
+  EXPECT_TRUE(safe_cmp::Le(1.0, 2.0));
+  EXPECT_FALSE(safe_cmp::Le(2, 1));
+  EXPECT_FALSE(safe_cmp::Le(2, 1.0));
+  EXPECT_FALSE(safe_cmp::Le(2.0, 1));
+  EXPECT_FALSE(safe_cmp::Le(2.0, 1.0));
+
+  EXPECT_TRUE(safe_cmp::Le(2, 2));
+  EXPECT_TRUE(safe_cmp::Le(2, 2.0));
+  EXPECT_TRUE(safe_cmp::Le(2.0, 2));
+  EXPECT_TRUE(safe_cmp::Le(2.0, 2.0));
+
+  EXPECT_TRUE(safe_cmp::Le(p1, p1));
+  EXPECT_TRUE(safe_cmp::Le(p1, p2));
+  EXPECT_FALSE(safe_cmp::Le(p2, p1));
+  EXPECT_TRUE(safe_cmp::Le(p2, p2));
+}
+
+TEST(SafeCmpTest, Gt) {
+  EXPECT_FALSE(safe_cmp::Gt(-1, 2));
+  EXPECT_FALSE(safe_cmp::Gt(-1, 2u));
+  EXPECT_TRUE(safe_cmp::Gt(2, -1));
+  EXPECT_TRUE(safe_cmp::Gt(2u, -1));
+
+  EXPECT_FALSE(safe_cmp::Gt(1, 2));
+  EXPECT_FALSE(safe_cmp::Gt(1, 2u));
+  EXPECT_FALSE(safe_cmp::Gt(1u, 2));
+  EXPECT_FALSE(safe_cmp::Gt(1u, 2u));
+  EXPECT_TRUE(safe_cmp::Gt(2, 1));
+  EXPECT_TRUE(safe_cmp::Gt(2, 1u));
+  EXPECT_TRUE(safe_cmp::Gt(2u, 1));
+  EXPECT_TRUE(safe_cmp::Gt(2u, 1u));
+
+  EXPECT_FALSE(safe_cmp::Gt(2, 2));
+  EXPECT_FALSE(safe_cmp::Gt(2, 2u));
+  EXPECT_FALSE(safe_cmp::Gt(2u, 2));
+  EXPECT_FALSE(safe_cmp::Gt(2u, 2u));
+
+  EXPECT_FALSE(safe_cmp::Gt(imin, imin));
+  EXPECT_FALSE(safe_cmp::Gt(imin, umax));
+  EXPECT_TRUE(safe_cmp::Gt(umax, imin));
+  EXPECT_FALSE(safe_cmp::Gt(umax, umax));
+
+  EXPECT_FALSE(safe_cmp::Gt(m1, m1));
+  EXPECT_FALSE(safe_cmp::Gt(m1, umax));
+  EXPECT_TRUE(safe_cmp::Gt(umax, m1));
+  EXPECT_FALSE(safe_cmp::Gt(umax, umax));
+
+  EXPECT_FALSE(safe_cmp::Gt(1, 2));
+  EXPECT_FALSE(safe_cmp::Gt(1, 2.0));
+  EXPECT_FALSE(safe_cmp::Gt(1.0, 2));
+  EXPECT_FALSE(safe_cmp::Gt(1.0, 2.0));
+  EXPECT_TRUE(safe_cmp::Gt(2, 1));
+  EXPECT_TRUE(safe_cmp::Gt(2, 1.0));
+  EXPECT_TRUE(safe_cmp::Gt(2.0, 1));
+  EXPECT_TRUE(safe_cmp::Gt(2.0, 1.0));
+
+  EXPECT_FALSE(safe_cmp::Gt(2, 2));
+  EXPECT_FALSE(safe_cmp::Gt(2, 2.0));
+  EXPECT_FALSE(safe_cmp::Gt(2.0, 2));
+  EXPECT_FALSE(safe_cmp::Gt(2.0, 2.0));
+
+  EXPECT_FALSE(safe_cmp::Gt(p1, p1));
+  EXPECT_FALSE(safe_cmp::Gt(p1, p2));
+  EXPECT_TRUE(safe_cmp::Gt(p2, p1));
+  EXPECT_FALSE(safe_cmp::Gt(p2, p2));
+}
+
+TEST(SafeCmpTest, Ge) {
+  EXPECT_FALSE(safe_cmp::Ge(-1, 2));
+  EXPECT_FALSE(safe_cmp::Ge(-1, 2u));
+  EXPECT_TRUE(safe_cmp::Ge(2, -1));
+  EXPECT_TRUE(safe_cmp::Ge(2u, -1));
+
+  EXPECT_FALSE(safe_cmp::Ge(1, 2));
+  EXPECT_FALSE(safe_cmp::Ge(1, 2u));
+  EXPECT_FALSE(safe_cmp::Ge(1u, 2));
+  EXPECT_FALSE(safe_cmp::Ge(1u, 2u));
+  EXPECT_TRUE(safe_cmp::Ge(2, 1));
+  EXPECT_TRUE(safe_cmp::Ge(2, 1u));
+  EXPECT_TRUE(safe_cmp::Ge(2u, 1));
+  EXPECT_TRUE(safe_cmp::Ge(2u, 1u));
+
+  EXPECT_TRUE(safe_cmp::Ge(2, 2));
+  EXPECT_TRUE(safe_cmp::Ge(2, 2u));
+  EXPECT_TRUE(safe_cmp::Ge(2u, 2));
+  EXPECT_TRUE(safe_cmp::Ge(2u, 2u));
+
+  EXPECT_TRUE(safe_cmp::Ge(imin, imin));
+  EXPECT_FALSE(safe_cmp::Ge(imin, umax));
+  EXPECT_TRUE(safe_cmp::Ge(umax, imin));
+  EXPECT_TRUE(safe_cmp::Ge(umax, umax));
+
+  EXPECT_TRUE(safe_cmp::Ge(m1, m1));
+  EXPECT_FALSE(safe_cmp::Ge(m1, umax));
+  EXPECT_TRUE(safe_cmp::Ge(umax, m1));
+  EXPECT_TRUE(safe_cmp::Ge(umax, umax));
+
+  EXPECT_FALSE(safe_cmp::Ge(1, 2));
+  EXPECT_FALSE(safe_cmp::Ge(1, 2.0));
+  EXPECT_FALSE(safe_cmp::Ge(1.0, 2));
+  EXPECT_FALSE(safe_cmp::Ge(1.0, 2.0));
+  EXPECT_TRUE(safe_cmp::Ge(2, 1));
+  EXPECT_TRUE(safe_cmp::Ge(2, 1.0));
+  EXPECT_TRUE(safe_cmp::Ge(2.0, 1));
+  EXPECT_TRUE(safe_cmp::Ge(2.0, 1.0));
+
+  EXPECT_TRUE(safe_cmp::Ge(2, 2));
+  EXPECT_TRUE(safe_cmp::Ge(2, 2.0));
+  EXPECT_TRUE(safe_cmp::Ge(2.0, 2));
+  EXPECT_TRUE(safe_cmp::Ge(2.0, 2.0));
+
+  EXPECT_TRUE(safe_cmp::Ge(p1, p1));
+  EXPECT_FALSE(safe_cmp::Ge(p1, p2));
+  EXPECT_TRUE(safe_cmp::Ge(p2, p1));
+  EXPECT_TRUE(safe_cmp::Ge(p2, p2));
+}
+
+}  // namespace rtc