Resolve an ambiguous function call by casting to StringPiece::size_type

base/string_piece_unittest.cc

Index: base/string_piece_unittest.cc
diff --git a/base/string_piece_unittest.cc b/base/string_piece_unittest.cc
index a29fe747e6db2ff3c7d3fe61def7c03402c45335..a8ab4ff20d798691909c238f576cac758ca7bd8b 100644
--- a/base/string_piece_unittest.cc
+++ b/base/string_piece_unittest.cc
@@ -664,9 +664,9 @@ TYPED_TEST(CommonStringPieceTest, CheckConstructors) {
   ASSERT_TRUE(str == BasicStringPiece<TypeParam>(str.c_str()));
   ASSERT_TRUE(TestFixture::as_string("hello") ==
               BasicStringPiece<TypeParam>(str.c_str(), 5));
-  ASSERT_TRUE(empty == BasicStringPiece<TypeParam>(str.c_str(), 0));
+  ASSERT_TRUE(empty == BasicStringPiece<TypeParam>(str.c_str(), 0U));
   ASSERT_TRUE(empty == BasicStringPiece<TypeParam>(NULL));
-  ASSERT_TRUE(empty == BasicStringPiece<TypeParam>(NULL, 0));
+  ASSERT_TRUE(empty == BasicStringPiece<TypeParam>(NULL, 0U));
   ASSERT_TRUE(empty == BasicStringPiece<TypeParam>());
   ASSERT_TRUE(str == BasicStringPiece<TypeParam>(str.begin(), str.end()));
   ASSERT_TRUE(empty == BasicStringPiece<TypeParam>(str.begin(), str.begin()));