3 files changed, 30 insertions, 1 deletions
diff --git a/third_party/BUILD.gn b/third_party/BUILD.gn
index 21d3d5db32..f6358147be 100644
--- a/third_party/BUILD.gn
+++ b/third_party/BUILD.gn
@@ -300,6 +300,7 @@ source_set("pdfium_base") {
     "base/numerics/safe_conversions_impl.h",
     "base/numerics/safe_math.h",
     "base/numerics/safe_math_impl.h",
+    "base/stl_util.h",
     "base/template_util.h",
   ]
 }
diff --git a/third_party/base/stl_util.h b/third_party/base/stl_util.h
new file mode 100644
index 0000000000..fcbe5882a2
--- /dev/null
+++ b/third_party/base/stl_util.h
@@ -0,0 +1,27 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef PDFIUM_THIRD_PARTY_BASE_STL_UTIL_H_
+#define PDFIUM_THIRD_PARTY_BASE_STL_UTIL_H_
+
+#include <vector>
+
+namespace pdfium {
+
+// To treat a possibly-empty vector as an array, use these functions.
+// If you know the array will never be empty, you can use &*v.begin()
+// directly, but that is undefined behaviour if |v| is empty.
+template <typename T>
+inline T* vector_as_array(std::vector<T>* v) {
+  return v->empty() ? nullptr : &*v->begin();
+}
+
+template <typename T>
+inline const T* vector_as_array(const std::vector<T>* v) {
+  return v->empty() ? nullptr : &*v->begin();
+}
+
+}  // namespace pdfium
+
+#endif  // PDFIUM_THIRD_PARTY_BASE_STL_UTIL_H_
diff --git a/third_party/third_party.gyp b/third_party/third_party.gyp
index 6ad8beb48c..1ec0509eb2 100644
--- a/third_party/third_party.gyp
+++ b/third_party/third_party.gyp
@@ -281,11 +281,12 @@
         'base/logging.h',
         'base/macros.h',
         'base/nonstd_unique_ptr.h',
-        'base/template_util.h',
         'base/numerics/safe_conversions.h',
         'base/numerics/safe_conversions_impl.h',
         'base/numerics/safe_math.h',
         'base/numerics/safe_math_impl.h',
+        'base/stl_util.h',
+        'base/template_util.h',
       ],
     },
   ],