Add missing operator<() to CFX_RetainPtr

core/fxcrt/cfx_retain_ptr_unittest.cpp

Index: core/fxcrt/cfx_retain_ptr_unittest.cpp
diff --git a/core/fxcrt/cfx_retain_ptr_unittest.cpp b/core/fxcrt/cfx_retain_ptr_unittest.cpp
index f9a4ecb74ffb6446209ebfa8644f2b7459859618..3168b5a4c7bfeb28d55a185e36da69cfc3a3afcf 100644
--- a/core/fxcrt/cfx_retain_ptr_unittest.cpp
+++ b/core/fxcrt/cfx_retain_ptr_unittest.cpp
@@ -225,6 +225,14 @@ TEST(fxcrt, RetainPtrNotEquals) {
   EXPECT_TRUE(obj1_ptr1 != obj2_ptr1);
 }
 
+TEST(fxcrt, RetainPtrLessThan) {
+  PseudoRetainable objs[2];
+  CFX_RetainPtr<PseudoRetainable> obj1_ptr(&objs[0]);
+  CFX_RetainPtr<PseudoRetainable> obj2_ptr(&objs[1]);
+  EXPECT_TRUE(obj1_ptr < obj2_ptr);
+  EXPECT_FALSE(obj2_ptr < obj1_ptr);
+}
+
 TEST(fxcrt, RetainPtrBool) {
   PseudoRetainable obj1;
   CFX_RetainPtr<PseudoRetainable> null_ptr;