Add explicit casts from size_t to uint32_t

mojo/public/cpp/bindings/tests/union_unittest.cc

Index: mojo/public/cpp/bindings/tests/union_unittest.cc
diff --git a/mojo/public/cpp/bindings/tests/union_unittest.cc b/mojo/public/cpp/bindings/tests/union_unittest.cc
index 65a23fad2ee1a94296c603f9fb0a5011633ecca6..e6e38de3f50cfca3f6d6a0f0443aca310d1c1441 100644
--- a/mojo/public/cpp/bindings/tests/union_unittest.cc
+++ b/mojo/public/cpp/bindings/tests/union_unittest.cc
@@ -499,7 +499,8 @@ TEST(UnionTest, Validation_UnionsInStruct) {
   Serialize_(small_struct.Pass(), &buf, &data);
 
   void* raw_buf = buf.Leak();
-  mojo::internal::BoundsChecker bounds_checker(data, size, 0);
+  mojo::internal::BoundsChecker bounds_checker(data,
+                                               static_cast<uint32_t>(size), 0);
   EXPECT_TRUE(internal::SmallStruct_Data::Validate(raw_buf, &bounds_checker));
   free(raw_buf);
 }
@@ -519,7 +520,8 @@ TEST(UnionTest, Validation_PodUnionInStruct_Failure) {
   data->pod_union.tag = static_cast<internal::PodUnion_Data::PodUnion_Tag>(100);
 
   void* raw_buf = buf.Leak();
-  mojo::internal::BoundsChecker bounds_checker(data, size, 0);
+  mojo::internal::BoundsChecker bounds_checker(data,
+                                               static_cast<uint32_t>(size), 0);
   EXPECT_FALSE(internal::SmallStruct_Data::Validate(raw_buf, &bounds_checker));
   free(raw_buf);
 }
@@ -537,7 +539,8 @@ TEST(UnionTest, Validation_NullUnion_Failure) {
       internal::SmallStructNonNullableUnion_Data::New(&buf);
 
   void* raw_buf = buf.Leak();
-  mojo::internal::BoundsChecker bounds_checker(data, size, 0);
+  mojo::internal::BoundsChecker bounds_checker(data,
+                                               static_cast<uint32_t>(size), 0);
   EXPECT_FALSE(internal::SmallStructNonNullableUnion_Data::Validate(
       raw_buf, &bounds_checker));
   free(raw_buf);
@@ -555,7 +558,8 @@ TEST(UnionTest, Validation_NullableUnion) {
   Serialize_(small_struct.Pass(), &buf, &data);
 
   void* raw_buf = buf.Leak();
-  mojo::internal::BoundsChecker bounds_checker(data, size, 0);
+  mojo::internal::BoundsChecker bounds_checker(data,
+                                               static_cast<uint32_t>(size), 0);
   EXPECT_TRUE(internal::SmallStruct_Data::Validate(raw_buf, &bounds_checker));
   free(raw_buf);
 }