Implement pure virtual method to fix build.

llvm-svn: 327431
diff --git a/llvm/unittests/DebugInfo/PDB/PDBApiTest.cpp b/llvm/unittests/DebugInfo/PDB/PDBApiTest.cpp
index f70fca7..4cc47aa 100644
--- a/llvm/unittests/DebugInfo/PDB/PDBApiTest.cpp
+++ b/llvm/unittests/DebugInfo/PDB/PDBApiTest.cpp
@@ -11,6 +11,7 @@
 
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/DebugInfo/PDB/IPDBEnumChildren.h"
+#include "llvm/DebugInfo/PDB/IPDBInjectedSource.h"
 #include "llvm/DebugInfo/PDB/IPDBLineNumber.h"
 #include "llvm/DebugInfo/PDB/IPDBRawSymbol.h"
 #include "llvm/DebugInfo/PDB/IPDBSession.h"
@@ -124,6 +125,10 @@
   std::unique_ptr<IPDBEnumTables> getEnumTables() const override {
     return nullptr;
   }
+
+  std::unique_ptr<IPDBEnumInjectedSources> getInjectedSources() const override {
+    return nullptr;
+  }
 };
 
 class MockRawSymbol : public IPDBRawSymbol {