Enable protobuf printing for open-source proto messages.

googletest/include/gtest/internal/gtest-internal.h

@@ -94,6 +94,12 @@ namespace proto2 {
 class MessageLite;
 }
 
+namespace google {
+namespace protobuf {
+class MessageLite;
+}
+}
+
 namespace testing {
 
 // Forward declarations.
@@ -881,10 +887,15 @@ class GTEST_API_ Random {
   typename std::remove_const<typename std::remove_reference<T>::type>::type
 
 // IsAProtocolMessage<T>::value is a compile-time bool constant that's
-// true if and only if T is type proto2::MessageLite or a subclass of it.
+// true if and only if T is type proto2::MessageLite or
+// google::protobuf::MessageLite or a subclass of one of them.
 template <typename T>
 struct IsAProtocolMessage
-    : public std::is_convertible<const T*, const ::proto2::MessageLite*> {};
+    : public std::integral_constant<
+          bool,
+          std::is_convertible<const T*, const ::proto2::MessageLite*>::value ||
+              std::is_convertible<
+                  const T*, const ::google::protobuf::MessageLite*>::value> {};
 
 // When the compiler sees expression IsContainerTest<C>(0), if C is an
 // STL-style container class, the first overload of IsContainerTest

googletest/test/gtest_unittest.cc

@@ -7115,6 +7115,10 @@ TEST(IsAProtocolMessageTest, ValueIsTrueWhenTypeIsAProtocolMessage) {
   EXPECT_TRUE(IsAProtocolMessage<::proto2::MessageLite>::value);
 }
 
+TEST(IsAProtocolMessageTest, ValueIsTrueWhenTypeIsAnOpenSourceProtocolMessage) {
+  EXPECT_TRUE(IsAProtocolMessage<::google::protobuf::MessageLite>::value);
+}
+
 // Tests that IsAProtocolMessage<T>::value is false when T is neither
 // ::proto2::Message nor a sub-class of it.
 TEST(IsAProtocolMessageTest, ValueIsFalseWhenTypeIsNotAProtocolMessage) {