[gn build] Merge r349167
diff --git a/llvm/utils/gn/secondary/llvm/lib/CodeGen/GlobalISel/BUILD.gn b/llvm/utils/gn/secondary/llvm/lib/CodeGen/GlobalISel/BUILD.gn
index 7147c82..df8a110 100644
--- a/llvm/utils/gn/secondary/llvm/lib/CodeGen/GlobalISel/BUILD.gn
+++ b/llvm/utils/gn/secondary/llvm/lib/CodeGen/GlobalISel/BUILD.gn
@@ -15,6 +15,7 @@
     "CallLowering.cpp",
     "Combiner.cpp",
     "CombinerHelper.cpp",
+    "GISelChangeObserver.cpp",
     "GlobalISel.cpp",
     "IRTranslator.cpp",
     "InstructionSelect.cpp",