Prefix string16 with base:: in ui/.

ui/gfx/utf16_indexing_unittest.cc

Index: ui/gfx/utf16_indexing_unittest.cc
diff --git a/ui/gfx/utf16_indexing_unittest.cc b/ui/gfx/utf16_indexing_unittest.cc
index da2f8f5b56c23d5032df1cc356063a18e35ac84a..e17bdc8043efa8120df23f73061618d4f20085d0 100644
--- a/ui/gfx/utf16_indexing_unittest.cc
+++ b/ui/gfx/utf16_indexing_unittest.cc
@@ -10,7 +10,7 @@ namespace gfx {
 TEST(UTF16IndexingTest, IndexOffsetConversions) {
   // Valid surrogate pair surrounded by unpaired surrogates
   const char16 foo[] = {0xDC00, 0xD800, 0xD800, 0xDFFF, 0xDFFF, 0xDBFF, 0};
-  const string16 s(foo);
+  const base::string16 s(foo);
   const size_t the_invalid_index = 3;
   for (size_t i = 0; i <= s.length(); ++i)
     EXPECT_EQ(i != the_invalid_index, IsValidCodePointIndex(s, i));